21138
domain: N
Appears in sequences
- Fibonacci sequence beginning 2, 12.at n=17A022368
- Number of forests of rooted trees where n dollars are spent and an n-node tree costs 2n-1 dollars.at n=23A038000
- Number of positive integers <= 2^n of form 3 x^2 + 3 y^2.at n=18A054161
- Number of partitions of n in which the sequence of frequencies of the summands is nondecreasing.at n=42A100883
- The number of 0's in the n-th stage of A164349.at n=15A164362
- 3-comma numbers: n occurs in the sequence S[k+1]=S[k]+10*last_digit(S[k-1])+first_digit(S[k]) for three different splittings n=concat(S[0],S[1]).at n=22A166513
- a(n) = 14*n^2 - 4*n.at n=39A195023
- a(n) = 680*2^n - 622.at n=5A305263
- Number of partitions of an n-set without blocks of size 8.at n=9A343668
- Number of n-step self-avoiding walks on the Laves graph with no non-contiguous adjacencies.at n=14A344040
- Positive numbers whose square starts and ends with exactly 44, and no 444.at n=9A348831
- G.f.: Sum_{k>=0} x^(k*(k+1)) / Product_{j=1..k} (1 - x^(2*j-1))^2.at n=51A376622
- G.f. A(x) satisfies A(x) = 1 + x * (1+x)^2 * A(x)^4.at n=6A378786