20497

Appears in sequences

• Numbers whose base-4 representation contains exactly four 0's and four 1's.at n=21A045037
• 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, 0), (-1, 0, 0), (-1, 1, 1), (1, 0, -1), (1, 1, 1)}.at n=8A149637
• Partial sums of A151791.at n=38A151792
• Expansion of e.g.f. exp(t*x)/(1 - x^2/t^2 - t^3* x^3).at n=80A158757
• Expansion of e.g.f.: exp(t*x)/(1 - x^2/t - t^3*x^3).at n=60A158785
• Numbers containing only 1's and 0's in their base-2, base-3, and base-4 representations.at n=16A258981
• Numbers n such that n, p=prime(n) and q=prime(p) have the same sum of digits.at n=34A261142
• Semiprimes whose binary and ternary representations are prime when read in decimal.at n=25A279052
• Expansion of e.g.f. exp(x) / (1 - x^3).at n=8A330044
• a(n) = (3*n+2)! * Sum_{k=0..n} 1 / (3*k+2)!.at n=2A337726
• G.f. A(x) satisfies: A(x) = x * exp(3 * Sum_{k>=1} (-1)^k * A(x^k) / k).at n=6A345885