A379915 a(n) is the deficiency of the odd squarefree semiprime A046388(n), divided by 2.

3, 5, 9, 11, 11, 15, 19, 17, 23, 21, 29, 31, 27, 35, 29, 35, 35, 43, 47, 39, 41, 53, 45, 59, 55, 59, 51, 65, 57, 59, 71, 79, 65, 83, 79, 89, 69, 83, 89, 71, 95, 91, 77, 107, 81, 109, 107, 103, 87, 119, 95, 115, 131, 125, 99, 119, 101, 139, 105, 143, 107, 137, 131

Offset

1,1

Links

Hugo Pfoertner, Table of n, a(n) for n = 1..10000

Formula

a(n) = (2*A046388(n) - sigma(A046388(n)))/2, where sigma is A000203.

a(n) = A033879(A046388(n))/2.

Prog

(PARI) \\ uses function a379915_17 from A379917
a379915_17(300, 2)

Crossrefs

Cf. A000203, A033879, A046388, A379916, A379917.

Sequence in context: A270780 A386268 A304251 * A309135 A088607 A296243

Adjacent sequences: A379912 A379913 A379914 * A379916 A379917 A379918

Keyword

nonn

Author

Hugo Pfoertner, Jan 06 2025

Status

approved