64050

Appears in sequences

• Numbers k such that the sum of the k-th triangular number and (k+2)-nd triangular number is a triangular number.at n=12A076049
• Product of Fibonacci and (shifted) triangular numbers.at n=15A086926
• Triangle T, read by rows, where T(n,k) = Sum_{j=1..n-k-1} [T^j](n-1,k) with T(n+1,n) = n+1 and T(n,n)=0 for n>=0, where T^n denotes the n-th matrix power of T.at n=36A132623
• Column 0 of triangle A132623.at n=7A132624
• a(n) = Sum_{k=1..n} k * sigma_2(k).at n=20A356125
• Triangular array read by rows. T(n,k) is the number of alternating permutations of [2n+1] having exactly 2k elements to the left of 1, n >= 0, 0 <= k <= n.at n=17A362582
• Triangular array read by rows. T(n,k) is the number of alternating permutations of [2n+1] having exactly 2k elements to the left of 1, n >= 0, 0 <= k <= n.at n=18A362582
• Numbers k such that prime(k), prime(k+1), prime(k+2), prime(k+3) and prime(k+4) all have the same last digit.at n=13A371390
• E.g.f. A(x) satisfies A(x) = 1 + (1/x) * (exp(x^2*A(x)) - 1).at n=7A392953