31647

Appears in sequences

• a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (Lucas numbers), t = A000201 (lower Wythoff sequence).at n=24A024474
• Number of nodes at the n-th level of the Inverse-Totient-Tree (ITT) with the root at 1, and edges connecting number m to all numbers k such that phi(k) = m.at n=13A058811
• Starting term of the smallest n-chain of numbers whose squares are permutations of the same digits.at n=22A085546
• a(n) = A000217(A000217(n))-n^2.at n=22A086602
• Vertex number of a rectangular spiral related to Fibonacci numbers and prime numbers. The distances between nearest edges of the spiral that are parallel to the initial edge are the Fibonacci numbers, while the distances between nearest edges perpendicular to the initial edge are the prime numbers.at n=38A160794
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 49", based on the 5-celled von Neumann neighborhood.at n=36A270016
• Number of Carlitz compositions having at least two identical parts.at n=20A285981
• Regular triangle read by rows where T(n,k) is the number of labeled simple graphs on n vertices where all non-isolated vertices have degree k.at n=41A319729
• Composite numbers k coprime to 13 such that k divides A006190(k-Kronecker(13,k)).at n=27A327653