31561

Appears in sequences

• Numbers n such that sum of squares of even digits of n equals sum of squares of odd digits of n.at n=33A076164
• Indices of prime tetranacci numbers.at n=10A104534
• Grow a binary tree using the following rules. Initially there is a single node labeled 1. At each step we add 1 to all labels less than 3. If a node has label 3 and zero or one descendants we add a new descendant labeled 1. Sequence gives sum of all labels at step n.at n=45A123015
• Smallest k such that 40^k mod k = n.at n=41A178201
• Number of 5 X n 0..1 arrays with diagonals and antidiagonals unimodal and rows nondecreasing.at n=10A223952
• Numbers m such that there exists at least one integer k < m such that m^2+1 and k^2+1 have the same prime factors.at n=14A282092
• Pairs of integers (x, y), such that x^2 + 1 and y^2 + 1, 1 < y < x, have the same distinct prime factors.at n=28A284477