-1991

Appears in sequences

• Triangle T(n, k) = binomial(binomial(n, 2) + k, k) + binomial(binomial(n, 2) + n-k, n-k) - binomial(binomial(n, 2) + n, n), read by rows.at n=16A176567
• Triangle T(n, k) = binomial(binomial(n, 2) + k, k) + binomial(binomial(n, 2) + n-k, n-k) - binomial(binomial(n, 2) + n, n), read by rows.at n=19A176567
• Values of n such that L(6) and N(6) are both prime, where L(k) = (n^2+n+1)*2^(2*k) + (2*n+1)*2^k + 1, N(k) = (n^2+n+1)*2^k + n.at n=14A226926
• Coefficient of x in minimal polynomial of the continued fraction [1^n,5,1,1,1,...], where 1^n means n ones.at n=5A265805
• Expansion of the series reversion of -1 + Product_{k>=1} (1 + x^(2*k-1)).at n=12A291646
• Signed recurrence over binary strict trees: a(n) = 1 - Sum_{x + y = n, 0 < x < y < n} a(x) * a(y).at n=36A300866