816480

Appears in sequences

• a(1) = 3, a(n) = smallest multiple of a(n-1) such that 10*a(n) + 1 is prime.at n=12A089325
• a(n) = n^2*binomial(n,2).at n=35A092364
• Triangle T(n,k) of numbers of connected (unicyclic) graphs with unique cycle of length k (3<=k<=n), on n labeled nodes.at n=25A098909
• G.f.: exp( Sum_{n>=1} sigma(n)*A002203(n)*x^n/n ) where A002203 is the companion Pell numbers.at n=11A203534
• Triangle T(n,k) of weakly graded (3+1)-free partially ordered sets (posets) on n labeled vertices with height k.at n=33A222866
• Number of integers k^5 that divide 1!*2!*3!*...*n!.at n=21A248823
• Triangle used for the integral of even powers of the sine and cosine functions.at n=43A254933
• Triangle read by rows: T(n,k) is the number of n-bead bracelets with exactly k different colored beads.at n=53A273891
• Triangle read by rows: T(n,k) is the number of chiral pairs of color loops of length n with exactly k different colors.at n=53A305541
• T(n,k) is the number of non-equivalent distinguishing colorings of the cycle on n vertices with exactly k colors (k>=1). Regular triangle read by rows, n >= 1, 1 <= k <= n.at n=53A309651
• Number of anti-run permutations of the prime indices of n!.at n=14A335407
• Number of permutations of [n] whose order is a multiple of n.at n=9A346121
• a(n) = n! * Sum_{k=0..floor(n/3)} (n - 3*k)^k/6^k.at n=9A356633
• Expansion of e.g.f. Sum_{k>=0} x^k / (1 - k*x^k/k!).at n=9A356667