20900

Appears in sequences

• Theta series of 10-d 11-modular Craig lattice A_10^(3).at n=12A028995
• Composite numbers divisible by the palindromic sum of their prime factors (counted with multiplicity).at n=33A046358
• Consider sequence of fractions A066657/A066658 produced by ratios of terms in A066720; let m = smallest integer such that all fractions 1/n, 2/n, ..., (n-1)/n have appeared when we reach A066720(m) = k; sequence gives values of m; set a(n) = -1 if some fraction i/n never appears.at n=21A066849
• a(n) = Bell(n+1) - 2^n + 1 + n, where Bell(i) is the i-th Bell number A000110(i).at n=8A094762
• Twice 13-gonal numbers: a(n) = n*(11*n - 9).at n=44A152997
• Number of ways to place zero or more nonadjacent 0,0 1,0 1,1 2,1 3,1 3,2 4,2 polyhexes in any orientation on a planar nXnXn triangular grid.at n=8A155322
• Averages of four consecutive cubes.at n=27A173965
• Partial sums of A079062.at n=38A177455
• a(n) = denominator(B°(2*n))/4 where the B°(n) are Zagier's modified Bernoulli numbers.at n=9A216912
• a(n) = 4*n*(n^2 + 2)/3.at n=25A217873
• Magic sums of 4 X 4 magic squares composed of odd squares.at n=5A271582
• Numbers with digit sum 11 that are multiples of 11.at n=34A283742
• Numbers that are a sum of both four and six consecutive prime numbers.at n=36A380433