31030

Appears in sequences

• Number of permutations of [n] with four inversions.at n=25A005287
• (Sum of digits of n)^6 - (sum of digits^6 of n).at n=15A069966
• Group the composite numbers so that the sum of the n-th group is a multiple of the n-th prime: (4), (6), (8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22), (24, 25), (26, 27, 28, 30, 32), (33, 34, ...), ... Sequence gives sum of n-th group.at n=27A074124
• Triangle read by rows: T(n,k) is the number of hill-free Schroeder paths of length 2n that have k weak ascents (1<=k<=n-1 for n>=2; k=1 for n=1). A Schroeder path of length 2n is a lattice path from (0,0) to (2n,0) consisting of U=(1,1), D=(1,-1) and H=(2,0) steps and never going below the x-axis. A hill is a peak at height 1. A weak ascent in a Schroeder path is a maximal sequence of consecutive U and H steps.at n=31A114691
• Triangle T, read by rows, equal to the matrix square of triangle A117418; also equals a column bisection of triangle A117418: column 2k+1 of T^(1/2) equals column k of T.at n=60A117427
• Number of reduced words of length n in the Weyl group A_28.at n=4A161571
• Number of partitions p of n such that (number of parts of p) - min(p) is not a part of p.at n=39A238548
• a(n) = n*(n + 1)*(7*n + 11)/6.at n=29A255687
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 246", based on the 5-celled von Neumann neighborhood.at n=40A271010
• Let S be any integer in the range 6 <= S <= 24. Sequence has the property that a(n)*S is the sum of all positive integers whose decimal expansion has <= n digits and contains at most three distinct nonzero digits d1, d2, d3 such that d1+d2+d3 = S.at n=4A328350