20501

Appears in sequences

• a(n) = n*(7*n^2 - 1)/6.at n=26A004126
• Odd octagonal numbers: (2n+1)*(6n+1).at n=41A014641
• Sums of 5 distinct powers of 4.at n=36A038473
• a(n) = n*(2*n+5)*(n-1)/6.at n=39A051925
• Octagonal numbers for which the sum of the digits is also an octagonal number.at n=10A117082
• Octagonal numbers for which the product of the digits is also an octagonal number.at n=36A117083
• Octagonal numbers for which both the sum and the product of the digits is also an octagonal number.at n=4A117084
• A106486-encodings of combinatorial games with value 2.at n=27A125995
• 3-almost prime octagonal numbers.at n=17A129927
• Triangle, read by rows, T(n, k) = binomial(n, k) for n < 2 and binomial(n, k) + 4^(n-1) * binomial(n-2, k-1) otherwise.at n=30A146988
• Triangle, read by rows, T(n, k) = binomial(n, k) for n < 2 and binomial(n, k) + 4^(n-1) * binomial(n-2, k-1) otherwise.at n=33A146988
• G.f. x^4*(2*x^2-1)/( (x^2-1)*(x^2+x-1)*(2*x^3-2*x^2+2*x-1) ).at n=22A175378
• Number of compositions (ordered partitions) of n where no pair of adjacent part sizes is relatively prime.at n=35A178470
• Number of triples (w,x,y) with all terms in {0,...,n} and w >= floor((x+y)/3).at n=30A212972
• a(n) = 25*n*(n + 1)/2 + 1.at n=40A262221
• Octagonal numbers with prime indices.at n=22A267144
• Squarefree composite numbers n such that b^n == b (mod gpf(n)) for every integer b, where gpf(n) = A006530(n).at n=41A276832
• a(n) = A005259(n) mod (n+1)^3.at n=41A289289
• Number of compositions of n into parts with distinct multiplicities and with exactly eight parts.at n=32A321778
• Number of ways to fill a Young diagram with positive integers summing to n such that the rows are weakly decreasing and the columns are weakly increasing.at n=19A323580