20951

Appears in sequences

• Number of n-covers of an unlabeled 3-set.at n=13A005745
• Truncated square pyramid numbers: a(n) = Sum_{k = n..2*n-1} k^2.at n=21A050410
• Pell pseudoprimes: odd composite numbers n such that P(n)-Kronecker(2,n) is divisible by n.at n=27A099011
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (-1, 0, 1), (0, 1, -1), (0, 1, 1), (1, -1, 0)}.at n=9A148874
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, 0, 1), (-1, 1, 1), (0, -1, 1), (1, 1, -1), (1, 1, 0)}.at n=8A149491
• Numbers with ordered partitions that have periods of length 5.at n=40A178572
• Number of (w,x,y) with all terms in {0,...,n} and w != max(|w-x|, |x-y|).at n=27A213501
• a(n) = A118478(n)*(A118478(n)+1) divided by the product of the first n primes.at n=10A215021
• Maximum value of the cyclic convolution of the first n positive integers with themselves.at n=40A294172
• Sum of all the parts in the partitions of n into 4 parts.at n=41A308775
• Composite numbers k such that Pell(k) == 1 (mod k).at n=30A319042
• Number of ways to write n as an ordered sum of 7 primes.at n=30A340963
• a(n) is the least number that can be written in exactly n ways as p*q + q*r + p*r where (p,q,r) is an unordered triple of distinct primes.at n=21A356457