133580

Appears in sequences

• a(1)=1, a(n)=ceiling(n/(n+1)*sum(k=1,n-1,a(k))).at n=19A082423
• Numbers k such that 8*R_k + 9*10^k + 1 is prime, where R_k = 11...11 is the repunit (A002275) of length k.at n=9A259139
• Numbers k such that 441*2^k+1 is prime.at n=38A323149
• Coefficient of x^n in the expansion of ( (1+x+x^2)^2 / (1+x) )^n.at n=10A372370