21860

Appears in sequences

• a(n) = Sum_{k=0..2n} (k+1) * A027113(n, 2n-k).at n=8A027138
• Decimal part of n-th root of a(n) starts with digit 8.at n=15A034085
• n+A001045(n+1).at n=15A081660
• Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0), ending on the vertical axis and consisting of n steps taken from {(-1, -1), (-1, 0), (-1, 1), (0, 1), (1, -1)}.at n=11A151420
• Number of (n+2)X(n+2) 0..1 matrices with each 3X3 subblock idempotent.at n=11A224551
• Number of length n+5 0..3 arrays with at most one downstep in every 5 consecutive neighbor pairs.at n=3A258727
• T(n,k)=Number of length n+k 0..3 arrays with at most one downstep in every k consecutive neighbor pairs.at n=31A258730
• Number of length n+4 0..3 arrays with at most one downstep in every n consecutive neighbor pairs.at n=4A258734
• Numbers m > 0 that have a divisor d > 1 with binomial(m+d, d) == 1 mod m.at n=37A290040
• Numbers that are not the difference of two binary palindromes (A006995).at n=45A290393
• Numbers k such that the ring of integers of Q(2^(1/k)) is not Z[2^(1/k)].at n=25A342390
• a(n) = Sum_{k=1..n} floor(n/(2*k-1))^k.at n=44A350147
• Numbers k for which phi(k) = phi(k''), where phi is the Euler totient function (A000010) and k'' the second arithmetic derivative of k (A068346).at n=38A352331
• Numbers k for which k = phi(k') + phi(k''), where phi is the Euler totient function (A000010), k' the arithmetic derivative of k (A003415) and k'' the second arithmetic derivative of k (A068346).at n=12A352332