20281

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has period 35.at n=34A020374
• Numbers n such that n and prime(n) end with the same three digits.at n=15A067841
• a(1)=1. a(n) = a(n-1) + sum of the triangular numbers which are among the first (n-1) terms of the sequence.at n=36A100963
• a(n) = 676*n + 1.at n=29A158386
• a(n) = 30*n^2 + 1.at n=26A158558
• Sequence defined by the recurrence formula a(n+1)=sum(a(p)*a(n-p)+k,p=0..n)+l for n>=1, with here a(0)=1, a(1)=9, k=0 and l=-1.at n=6A177166
• Number of (n+1) X 9 binary arrays with every 2 X 2 subblock commuting with each of its horizontal and vertical 2 X 2 subblock neighbors.at n=9A186461
• G.f. A(x) satisfies: (1 - x) = A(x)*A(x^2)^2*A(x^3)^3*A(x^4)^4* ... *A(x^k)^k* ...at n=41A307656