A354869 Positions of odd terms in A354866, the Dirichlet inverse of A122111.

1, 4, 8, 9, 18, 25, 27, 32, 36, 49, 50, 54, 64, 72, 75, 98, 100, 108, 121, 125, 147, 150, 162, 169, 196, 200, 216, 225, 242, 243, 245, 250, 256, 289, 294, 300, 324, 338, 343, 361, 363, 375, 392, 441, 450, 484, 486, 490, 500, 507, 512, 529, 576, 578, 588, 600, 605, 675, 676, 686, 722, 726, 729, 735, 750, 841, 845

Offset: 1

Author

Antti Karttunen, Jun 09 2022

Keywords

• nonn

Comments

Apparently no squarefree terms after the initial 1.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..8192; all terms <= 2^20
• Index entries for sequences computed from indices in prime factorization

Crossrefs

Cf. A122111, A354866, A354868 (characteristic function).

Programs

PARI

A122111(n) = if(1==n,n,my(f=factor(n), es=Vecrev(f[,2]),is=concat(apply(primepi,Vecrev(f[,1])),[0]),pri=0,m=1); for(i=1, #es, pri += es[i]; m *= prime(pri)^(is[i]-is[1+i])); (m));
memoA354866 = Map();
A354866(n) = if(1==n,1,my(v); if(mapisdefined(memoA354866,n,&v), v, v = -sumdiv(n,d,if(dA122111(n/d)*A354866(d),0)); mapput(memoA354866,n,v); (v)));
A354868(n) = (A354866(n)%2);
isA354869(n) = A354868(n);