21137

Appears in sequences

• a(n) = a(n-1) + a(n-2) + 1, with a(0) = 1 and a(1) = 11.at n=17A022325
• Sum of first n 6-almost primes.at n=36A086052
• Row sums of triangle A131245.at n=13A131246
• 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, 1, -1), (1, -1, 0), (1, 0, 1), (1, 1, -1)}.at n=9A148855
• Numbers with d digits (d>0) which have at least 2d distinct primes as substrings.at n=13A168167
• Number of n X 2 binary arrays with an element zero only if there are an even number of ones to its left and an even number of ones above it.at n=12A183314
• Replace the word A214317(n) with its position in A007931.at n=13A214318
• Number G(n,k) of set partitions of {1,...,n} into sets of size at most k; triangle G(n,k), n>=0, 0<=k<=n, read by rows.at n=52A229223
• The partition function G(n,7).at n=9A229224
• Regular triangle read by rows where T(n, k) is the number of set partitions of {1, ..., n} with no block containing k cyclically successive vertices, n >= 1, 2 <= k <= n + 1.at n=42A323955