A349790 a(1) = 1; a(n) = -Sum_{d|n, d < n} lpf(n/d) * a(d).

1, -2, -3, 2, -5, 10, -7, -2, 6, 18, -11, -18, -13, 26, 27, 2, -17, -32, -19, -34, 39, 42, -23, 26, 20, 50, -12, -50, -29, -138, -31, -2, 63, 66, 65, 88, -37, 74, 75, 50, -41, -202, -43, -82, -90, 90, -47, -34, 42, -112, 99, -98, -53, 88, 105, 74, 111, 114, -59, 370

Offset

1,2

Comments

Dirichlet inverse of A020639.

Links

Table of n, a(n) for n=1..60.

Eric Weisstein's World of Mathematics, Least Prime Factor

Mathematica

a[1] = 1; a[n_] := a[n] = -Sum[(FactorInteger[n/d][[1, 1]]) a[d], {d, Most @ Divisors[n]}]; Table[a[n], {n, 1, 60}]

Crossrefs

Cf. A020639, A349789.

Sequence in context: A147294 A296662 A353299 * A335362 A371395 A059098

Adjacent sequences: A349787 A349788 A349789 * A349791 A349792 A349793

Keyword

sign

Author

Ilya Gutkovskiy, Nov 30 2021

Status

approved