19428

Appears in sequences

• Expansion of (1-2*x)/((1-x)^3*(1-4*x)).at n=7A028814
• Numbers m having the same sum of divisors as m+20 has.at n=32A181647
• a(n) = 1 - 2^(n+1) + 3^(n+2).at n=6A185940
• a(n) is the optimal wire-length for an n X n grid.at n=27A195647
• Numbers n such that n is the average of four consecutive primes n-5, n-1, n+1 and n+5.at n=34A258088
• Numbers n such that n^2048 + (n+1)^2048 is prime.at n=17A274235
• Numbers missing from A001033 despite satisfying the necessary congruence conditions (see comments).at n=29A274470
• Triangle read by rows: T(n,m) (n >= m >= 1) = number of line segments formed by drawing the lines connecting any two of the 2*(m+n) perimeter points of an m X n grid of squares.at n=48A331454
• a(n) is the determinant of the 2 X 2 matrix whose entries (when read by rows) are the n-th primes ending in 1, 3, 7, 9 respectively.at n=10A335592