31148

Appears in sequences

• Numbers k that divide the alternating sum sigma(1) - sigma(2) + sigma(3) - sigma(4) + ... + ((-1)^(k+1))*sigma(k).at n=12A067931
• Triangle T, read by rows, that satisfies: T(n,k) = [T^2](n-1,k) for n>k+1>=1, with T(n,n) = 1 and T(n+1,n) = n+1 for n>=0, where T^2 is the matrix square of T.at n=58A109152
• A doubly-fractal sequence. Erase the first (leftmost) digit of every integer: what is left is the sequence itself. The erased digits, one by one, form also the sequence itself.at n=43A127274
• a(n) = prime(n)*prime(n+1) + prime(n+2).at n=39A292926
• Number of refinement sequences n -> ... -> {1}^n, where in each step every single part of a nonempty selection of parts is replaced by a partition of itself into smaller parts (in weakly decreasing order).at n=8A327697
• a(n) = index in A377912 (or, equally, in A342042) of the first n-digit term.at n=5A377918