26811

Appears in sequences

• Numbers k that divide the (right) concatenation of all numbers <= k written in base 3 (most significant digit on left).at n=27A029448
• Numbers k such that k^2 = x^3 + y^4 with positive integers x, y.at n=33A087209
• G.f. A(x) satisfies both A(-x)*A(x) = A(x^2) and xA(x)^2 = B(xA(x^2)) where B(x) = x*(1+x)/(1-x).at n=24A091188
• Triangular sequence produced from symmetrical power of two matrices of the general type: M={{1, 2, 4, 8}, {2, 1, 2, 4}, {4, 2, 1, 2}, {8, 4, 2, 1}}.at n=32A129964
• O.g.f.: exp( Sum_{n>=1} A067692(n)*x^n/n ), where A067692(n) = [sigma(n)^2 + sigma(n,2)]/2.at n=15A180608
• a(n) = n^2 + 731*n + 1.at n=35A180919
• a(n) = n! mod 3^n.at n=10A212309
• Sum of quadratic residues of (n-th prime == 3 mod 4).at n=34A282035
• Let p = n-th prime == 3 mod 8; a(n) = sum of quadratic residues mod p.at n=17A282723
• a(n) is the number of triangles (up to congruence) with integer coordinates that have perimeter strictly less than n.at n=45A298121
• Triangle T(n,k), n>=2, 2 <= k <= A214046(n), read by rows, where T(n,k) = n! mod k^n.at n=19A340810
• Number of incongruent n-sided Reinhardt polygons.at n=62A374832