31803

Appears in sequences

• 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, 1, 0), (0, 0, -1), (1, 0, -1), (1, 0, 1)}.at n=9A149251
• Numbers k such that 9*10^k + 19 is prime.at n=29A272622
• G.f.: Sum_{n>=0} (n+1) * x^n * (1 + x^n)^n / (1 + x^(n+1))^(n+2).at n=42A326285
• a(n) equals the coefficient of x^(n*(n+1)) in Sum_{m>=0} (m+1) * x^m * (1 + x^m)^m / (1 + x^(m+1))^(m+2) for n >= 0.at n=6A326286
• Numbers k such that k and k+2 are both A000120-perfect numbers (A175522).at n=39A360639
• a(n) is the start of the least run of exactly n consecutive odd numbers that are A000120-perfect numbers (A175522).at n=2A360640