A197775 Partial sums of A197774.

1, 0, -1, -1, -2, -1, -2, -2, -2, -1, -2, -2, -3, -2, -1, 0, -1, -1, -2, -2, -1, 0, -1, -1, -1, 0, 0, 0, -1, -2, -3, -3, -2, -1, 0, 0, -1, 0, 1, 1, 0, -1, -2, -2, -2, -1, -2, -3, -3, -3, -2, -2, -3, -3, -2, -2, -1, 0, -1, -1, -2, -1, -1, -1, 0, -1, -2, -2, -1, -2, -3, -3

Offset

1,5

Links

Table of n, a(n) for n=1..72.

StackExchange, Question 73354

Mathematica

Accumulate@ Table[If[n == 1, 1, Apply[Times, FactorInteger[n] /. {p_, e_} /; p > 0 :> If[IntegerQ@ Sqrt@ e, (-1)^Sqrt@ e, 0]]], {n, 72}] (* Michael De Vlieger, Jan 27 2019 *)

Prog

(PARI) f(n) = {my(f=factor(n)[, 2]); prod(i=1, #f, if(issquare(f[i]), (-1)^sqrtint(f[i]), 0)); }; \\ A197774
a(n) = sum(k=1, n, f(k)); \\ Michel Marcus, Jan 27 2019

Crossrefs

Cf. A197774.

Sequence in context: A343240 A145866 A103318 * A002321 A043530 A297771

Adjacent sequences: A197772 A197773 A197774 * A197776 A197777 A197778

Keyword

sign

Author

A. Neves, Oct 18 2011

Status

approved