121716

Appears in sequences

• Describe the n-th triangular number A000217(n).at n=23A045986
• Triangle read by rows: T(n,k) = k!*binomial(n-1,k-1)*Stirling2(n,k), 1 <= k <= n.at n=30A048743
• "Look and Say" (or LS) transform of A079342(n). These terms are such that A079342(n) divides a(n).at n=13A079350
• Convolution of the central binomial coefficients A000984(n) and (-2)^n.at n=10A167481
• Numbers divisible by both the sum of the squares of their digits and the product of their digits.at n=11A244857
• G.f.: Sum_{k>=1} x^(2*k)/(1+x^(2*k)) * Product_{k>=1} (1+x^k)/(1-x^k).at n=30A305122