Search results
Results from the WOW.Com Content Network
An integer sequence is computable if there exists an algorithm that, given n, calculates a n, for all n > 0. The set of computable integer sequences is countable.The set of all integer sequences is uncountable (with cardinality equal to that of the continuum), and so not all integer sequences are computable.
In number theory, the aliquot sum s(n) of a positive integer n is the sum of all proper divisors of n, that is, all divisors of n other than n itself. That is, = |,. It can be used to characterize the prime numbers, perfect numbers, sociable numbers, deficient numbers, abundant numbers, and untouchable numbers, and to define the aliquot sequence of a number.
The number 4 is not untouchable, as it is equal to the sum of the proper divisors of 9: 1 + 3 = 4. The number 5 is untouchable, as it is not the sum of the proper divisors of any positive integer: 5 = 1 + 4 is the only way to write 5 as the sum of distinct positive integers including 1, but if 4 divides a number, 2 does also, so 1 + 4 cannot be ...
Alternatively, replace the 3n + 1 with n ′ / H(n ′) where n ′ = 3n + 1 and H(n ′) is the highest power of 2 that divides n ′ (with no remainder). The resulting function f maps from odd numbers to odd numbers. Now suppose that for some odd number n, applying this operation k times yields the number 1 (that is, f k (n) = 1).
Some graphing calculators, such as the Casio 9860 series, HP-49/50 series and HP Prime, TI-84 Plus, TI-89, and TI-Nspire, the TI-83 Plus with the PrettyPt [1] add-on, or the TI-84 Plus with the same add-on or the "MathPrint"-enabled OSes, can perform pretty-printing. Additionally, a number of newer scientific calculators are equipped with dot ...
The number of ways of writing n as an ordered sum in which no term is 2 is P(2n − 2). For example, P(6) = 4, and there are 4 ways to write 4 as an ordered sum in which no term is 2: 4 ; 1 + 3 ; 3 + 1 ; 1 + 1 + 1 + 1. The number of ways of writing n as a palindromic ordered sum in which no term is 2 is P(n).
While such acceptance is subjective, and often depends on individual coding habits, the following are common examples: the use of 0 and 1 as initial or incremental values in a for loop, such as for (int i = 0; i < max; i += 1) the use of 2 to check whether a number is even or odd, as in isEven = (x % 2 == 0), where % is the modulo operator
Even and odd numbers have opposite parities, e.g., 22 (even number) and 13 (odd number) have opposite parities. In particular, the parity of zero is even. [2] Any two consecutive integers have opposite parity. A number (i.e., integer) expressed in the decimal numeral system is even or odd according to whether its last digit is even or odd. That ...