23391

Appears in sequences

• a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (odd natural numbers), t = (primes).at n=32A024603
• Numbers that are the products of distinct substrings (>1) of themselves and do not end in 0.at n=28A059470
• Numbers n such that p(7n) is prime, where p(n) is the number of partitions of n.at n=33A114167
• Number of permutations of length n which avoid the patterns 1234, 2143, 3421.at n=27A116842
• a(n) = 289*n^2 - 2*n.at n=8A158252
• The Wiener index of the Dutch windmill graph D(6,n) (n>=1).at n=22A180578
• Number of proper diagonals of the n-dimensional associahedron (i.e., diagonals that are not included in lower dimension faces).at n=5A257887
• Expansion of 1/(1 - Sum_{k>=0} x^((2*k+1)^2)).at n=56A280863
• Zerofree numbers k such that the product (m+n)*p, where m,n are the first and the last digits of k, and p is the number which is the part of k between m and n, is a divisor of k.at n=28A320292
• Triangle read by rows: T(n,k) is the number of planar tanglegrams of size n with 0 <= k < n leaf-matched pairs. A leaf matched pair is a pair of non-leaf vertices (u,v) in the tanglegram such that the induced subtrees rooted and u and v also form a tanglegram (equivalently, the leaves in these two subtrees are matched by the matching that forms the original tanglegram).at n=29A349409
• Triangle read by rows: T(n,k) is the number of planar tanglegrams of size n with irreducible component of size k.at n=35A371659