21021
domain: N
Appears in sequences
- a(n) = n^2 written in base 3.at n=14A001738
- a(n) = (1/12)*(n+5)*(n+1)*n^2.at n=21A014205
- Odd numbers to the right of the central elements of the (2,3)-Pascal triangle A029600.at n=34A029616
- Distinct odd numbers in (3,2)-Pascal triangle A029618.at n=51A029626
- Odd numbers to left of central elements of the (3,2)-Pascal triangle A029618.at n=39A029630
- Numbers k such that 105*2^k+1 is prime.at n=42A032402
- Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 2,1,0.at n=4A037527
- Triangle of numbers of Dyck paths.at n=40A039797
- Triangle read by rows: numbers of Dyck paths.at n=40A039798
- Denominators of continued fraction convergents to sqrt(713).at n=10A042373
- a(n) = binomial(n+4,4)*(2*n+1).at n=10A051880
- a(n) = (n+1)*binomial(n+8, 8).at n=6A056003
- n repeated in decimal representation, but separated by enough zeros that the square has the pattern (n^2)(2n^2)(n^2).at n=20A077431
- Numbers whose name in American English is a word-palindrome, reading the same forward and backward.at n=29A081365
- a(n) = (4*n+3)*(4*n+7).at n=35A085027
- Solutions to A096509[x]=6; number of prime-powers [including primes] in the neighborhood of x with Ceiling[Log[x]] radius equals 6.at n=21A096517
- Structured small rhombicosidodecahedral numbers.at n=10A100148
- Table of denominators of coefficients of certain rational polynomials.at n=27A101023
- A sum of Jacobi transforms of 10^n.at n=4A110253
- Number triangle T(n,k) = binomial(n,k)*binomial(2n,n-k).at n=29A110608