19617

Appears in sequences

• [ n(n-1)(n-2)(n-3)/13 ].at n=24A011923
• a(n) = Sum_{k=0..floor(n/2)} T(n-k,k), T given by A026758.at n=19A026768
• a(n) = a(n-1) + a(m) for n >= 4, where m = 2*n - 2 - 2^(p+1) and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1, a(2) = 2, and a(3) = 3.at n=31A050051
• Triangle T(n,k) read by rows giving number of underdiagonal lattice paths from (0,0) to (n,k) using steps R=(1,0), V=(0,1) and D=(2,1).at n=52A071945
• Number of primes == 1 (mod 10) less than 10^n.at n=5A073505
• Expansion of (1+x^3)/((1-x)^3*(1-x^2)^3*(1-x^3)).at n=19A107351
• Triangle in A071945 with rows reversed.at n=47A108075
• Ceiling(n*exp(sec n)).at n=29A134898
• T(n,k)=Number of (n+1)X(k+1) 0..4 arrays with every 2X2 subblock commuting with each of its horizontal and vertical 2X2 subblock neighbors.at n=15A186484
• T(n,k)=Number of (n+1)X(k+1) 0..4 arrays with every 2X2 subblock commuting with each of its horizontal and vertical 2X2 subblock neighbors.at n=20A186484
• T(n,m)=Number of (n+1)X2 0..m arrays with every 2X2 subblock commuting with each of its vertical 2X2 subblock neighbors.at n=41A187363
• a(n) is the smallest number k > 0 such that k, k + 1, ... , k + n - 1 are nonprime numbers, but k + n is prime.at n=44A230358
• Number of 3-uniform hypergraphs on n labeled vertices where every two edges have exactly one vertex in common.at n=8A323299
• Start with a(0) = a(1) = 1. If a(n) = n is the rightmost term defined so far, let a(m) = m := n + a(n-1). If the terms between a(n) and a(m) are undefined, let a(n+1) = a(n) + a(m) and if m > n+1, a(m-1) = a(n+1) + a(m).at n=20A333375
• The smallest number in base n such that two digits (and no fewer) need to be changed to get a prime.at n=37A370531