A275342 2-adic valuation of iterated triangular numbers, starting with 2.

1, 0, 1, 0, 0, 2, 1, 0, 0, 0, 0, 2, 1, 0, 1, 0, 0, 0, 3, 2, 1, 0, 0, 2, 1, 0, 1, 0, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 1, 0, 2, 1, 0, 0, 2, 1, 0, 2, 1, 0, 0, 2, 1, 0, 0, 0, 3, 2, 1, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 2, 1, 0, 1, 0, 3, 2, 1, 0, 0, 0, 1, 0, 0, 0, 2, 1, 0, 2, 1, 0, 0, 0, 0, 2, 1, 0, 0, 4, 3, 2, 1, 0, 0, 4, 3, 2, 1, 0, 2, 1, 0, 1, 0, 0, 0, 1

Offset

1,6

Links

Table of n, a(n) for n=1..130.

Formula

Writing t(1) = 2, t(n+1) = t(n)(t(n)+1)/2, the sequence is nu_2 (t(n)), where nu_2 (x) is the exponent of the highest power of 2 dividing x.

a(n) = A007814(A007501(n)). - Michel Marcus, Jul 23 2016

Example

t(1) = 2, t(2) = 3, t(3) = 6, t(4) = 21, so a(1) = 1, a(2) = 0, a(3) = 1, a(4) = 0.

Crossrefs

Cf. A007501, A007814, A117872.

Sequence in context: A112208 A339089 A048158 * A246838 A219479 A113448

Adjacent sequences: A275339 A275340 A275341 * A275343 A275344 A275345

Keyword

nonn

Author

Jeffrey Shallit, Jul 23 2016

Status

approved