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

1,2

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

Prog

(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(d<n, A122111(n/d)*A354866(d), 0)); mapput(memoA354866, n, v); (v)));
A354868(n) = (A354866(n)%2);
isA354869(n) = A354868(n);

Crossrefs

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

Sequence in context: A089765 A116030 A116020 * A378172 A213015 A064393

Adjacent sequences: A354866 A354867 A354868 * A354870 A354871 A354872

Keyword

nonn

Author

Antti Karttunen, Jun 09 2022

Status

approved