20919

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 96.at n=33A031594
• McKay-Thompson series of class 12C for the Monster group.at n=13A058206
• Numbers n such that phi(phi(n)) + sigma(sigma(n)) - phi(sigma(n)) - sigma(phi(n)) = sigma(n).at n=4A066946
• Denominators a(n) of Pythagorean approximations b(n)/a(n) to Pi.at n=5A195544
• a(n) = smallest number that is the sum of 2n - 1, 2n + 1, and 2n + 3 consecutive primes.at n=8A288172
• Partial sums of A294016.at n=44A294017
• Number of quadrilateral regions in a "frame" of size n X n (see Comments in A331776 for definition), divided by 8.at n=25A332596
• The positive odd numbers x such that x = c^2 - y and +-x = a +- y, where (a,b,c) is a primitive Pythagorean triple (PPT), a is odd and y is an even positive integer.at n=32A357535
• Consecutive states of the linear congruential pseudo-random number generator (25173*s+13849) mod 2^16 when started at s=1.at n=10A383940
• Expansion of (1/x) * Series_Reversion( x / (1 + x^4 * (1 + x)^2) ).at n=20A389130