20738

Appears in sequences

• Coordination sequence for C_3 lattice: a(n) = 16*n^2 + 2 (n>0), a(0)=1.at n=36A010006
• Tanimoto triangle read by rows: T(n,k) = number of "parity-alternating permutations" (PAPS) of n symbols with k ascents.at n=59A125300
• Tanimoto triangle read by rows: T(n,k) = number of "parity-alternating permutations" (PAPS) of n symbols with k ascents.at n=61A125300
• Appearance radii of visible vectors in the medial axis test mask for the Euclidean distance in Z^2.at n=19A171988
• a(n) = F(n+1)^2, if n>=0 is even (F=A000045) and a(n) = (L(2n+2)+8)/5, if n is odd (L=A000204).at n=11A208176
• Triangle read by rows: number of permutations of [1..n] with k progressions of rise 2, distance 1 and length 3 (n >= 0, k >= 0).at n=35A216716
• Least number m such that there exist exactly n pairs of numbers (a,b), 0 < a < b < m, such that a+b, a+m, and b+m are all squares.at n=26A246766
• Composite numbers n such that Sum_{k = 0..n} (-1)^k * C(n,k) * C(2*n,k) == -1 (mod n^3) (see A234839).at n=32A268303
• Number of ten-prime Carmichael numbers less than 10^n.at n=3A299710
• Numbers of the form k^2 + 2 that are the sums of two squares.at n=14A329170
• a(n) = F(n+3) * F(n+1) + (-1)^n where F(n) = A000045(n) are the Fibonacci numbers.at n=9A338225
• Semiprimes of the form k^2 + 2.at n=40A360739
• Expansion of Sum_{k>0} x^(3*k)/(1 - k*x^k)^3.at n=26A363644