20825

Appears in sequences

• a(n) = 1^2 + 3^2 + 5^2 + 7^2 + ... + (2*n-1)^2 = n*(4*n^2 - 1)/3.at n=25A000447
• Degrees of irreducible representations of Held group He.at n=28A003912
• a(n) = n*(n+1)^2/2.at n=34A006002
• Dodecahedral numbers: a(n) = n*(3*n - 1)*(3*n - 2)/2.at n=17A006566
• Binomial coefficient C(n,48).at n=3A011001
• Odd tetrahedral numbers: a(n) = (4*n+1)*(4*n+2)*(4*n+3)/6.at n=12A015219
• Binomial coefficients C(51,n).at n=3A017767
• (prime(n)-5)(prime(n)-7)(prime(n)-9)/48.at n=25A030002
• a(n) = (prime(n) - 1)*(prime(n) - 3)*(prime(n) - 5)/48.at n=25A030004
• Numbers n such that n*phi(n-1) is a perfect square.at n=20A069069
• a(n) = binomial(n, smallest prime factor of n).at n=50A080211
• a(n) = n*(2*n+1)^2.at n=17A084367
• Group the natural numbers such that the n-th group sum is divisible by the n-th triangular number: (1), (2, 3, 4), (5, 6, 7), (8, 9, 10, 11, 12), (13, 14, 15, 16, 17), (18, 19, 20, 21, 22, 23, 24), ... Sequence contains the group sum.at n=33A086500
• Numerators in the fractional coefficients that form the partial quotients of the continued fraction representation of the inverse tangent of 1/x.at n=8A110255
• Numerators in the coefficients that form the odd-indexed partial quotients of the continued fraction representation of the inverse tangent of 1/x.at n=4A110257
• Main diagonal of triangle A119937.at n=7A119939
• Numerator of Sum_{k=0..n} 1/binomial(n,k)^4.at n=4A128152
• Partial sums of A006000.at n=19A133252
• Tetrahedral numbers n*(n+1)*(n+2)/6 with n, n+1 and n+2 nonprime.at n=12A152622
• Sequence related to Hankel transform of super-ballot numbers.at n=23A156126