20808

Appears in sequences

• a(n) = n^2*(n^2 - 1)/4.at n=17A006011
• a(n) = (1/4)*floor(n/2)*floor((n-1)/2)*floor((n-2)/2)*floor((n-3)/2).at n=36A028723
• Octahedral torus number: a(n) = n^2 + 2*(Sum_{k=1..n-1} k^2) - 2*(floor((n+1)/2)^2 + 2*(Sum_{k=1..floor((n+1)/2)-1} k^2)) + (1 - (-1)^n)/2.at n=34A050442
• a(n) is the cototient of n^3.at n=33A053192
• Low-temperature partition function expansion for Kagome net (Potts model, q=4).at n=14A057405
• Number of orbits of length n under the full 17-shift (whose periodic points are counted by A001026).at n=3A060220
• Nonpalindromic numbers k such that k is not divisible by 10 and k*R(k) is a square, where R(k) is the reversal of k (A004086).at n=25A062917
• Numbers k such that all the following properties hold: (i) k*reverse(k) is a square; (ii) k != reverse(k); (iii) k and reverse(k) are not both squares; and (iv) k and reverse(k) have the same number of digits.at n=14A082994
• Sixth column (m=5) of (1,4)-Pascal triangle A095666.at n=14A095668
• Powerful numbers (definition 1) sandwiched between twin primes.at n=9A113839
• Wiener index of the prism graph Y_n on 2n nodes.at n=33A138179
• a(n) = ((prime(n))^4-(prime(n))^2)/4.at n=6A138420
• Averages of twin prime pairs of A074378.at n=12A154563
• Averages of twin prime pairs k such that k*2 and k/2 are squares.at n=8A154670
• a(n) = 16*n^2 + 2*n.at n=35A158056
• Nearest k to j such that k*(2^j-1)+1 is prime where j=A000043(n) and 2^j-1 = Mersenne-prime(n) = A000668(n). If there are two k values equidistant from j, each of which produces a prime, the larger of the two gets added to the sequence.at n=25A159585
• Right edge of triangular table A138612.at n=37A166019
• Numbers of the form p^3*q^2*r^2 where p, q, and r are distinct primes.at n=11A179695
• Sum of positive cranks minus the sum of positive ranks of all partitions of n.at n=43A195012
• a(n) = 18*n^2.at n=34A195321