21328

Appears in sequences

• a(n) = n*(n+1)*(4*n+5)/6.at n=31A016061
• Scaled triangle A067327.at n=31A067328
• Imaginary part of absolute Gaussian perfect numbers, in order of increasing magnitude.at n=39A102532
• Admirable numbers n such that the subtracted divisor is > sqrt(n).at n=32A109321
• Number of elements in wreath product C_2 wr S_n that alternate up/not-up with respect to a weak product ordering.at n=6A153741
• Numbers d*p where d is a perfect number and p<d a prime not dividing d.at n=19A165772
• Number of right triangles on a (n+1)X8 grid.at n=13A189812
• Alternating sums of the squares of the numbers in sequence A080253.at n=3A217488
• Expansion of 1/(1 - x - x^2 + x^7 - x^9).at n=22A225394
• Number n such that the sum of its proper evil divisors (A001969) equals n.at n=29A230587
• Triangle read by rows: T(n,k) = 2^k*A235998(n,k), n>=1, k>=1.at n=34A235999
• Subsequence of lesser of 2 terms of A095301 that are 2 apart.at n=6A248083
• Numbers k such that 33*10^k + 7 is prime.at n=26A275285
• Number of n X 2 0..1 arrays with the number of 1's horizontally, antidiagonally or vertically adjacent to some 0 equal to the number of 0's adjacent to some 1, with top left element zero.at n=8A284193
• T(n,k) = Number of n X k 0..1 arrays with the number of 1's horizontally, antidiagonally or vertically adjacent to some 0 equal to the number of 0's adjacent to some 1, with top left element zero.at n=46A284199
• Number of set partitions of [n] with alternating parity of elements and exactly six blocks.at n=7A305780
• Triangular array read by rows: T(n,k) (2 <= k <= n) is the smallest number whose representations in bases n and k both consist of repeated identical blocks of digits.at n=19A317168
• a(n) = (n!)^3 * Sum_{k=0..n} k^2/(k!)^3.at n=4A368771