A359081 a(n) is the least number k such that A246600(k) = n, and -1 if no such k exists.

1, 3, 39, 15, 175, 63, 1275, 255, 1215, 891, 495, 6975, 14175, 26367, 13311, 8127, 20475, 42735, 95931, 69615, 36855, 24255, 404415, 4095, 96255, 423423, 253935, 98175, 913275, 165375, 507375, 130815, 3198975, 1576575, 203775, 2154495, 4398975, 1616895, 1556415

Offset: 1

Author

Amiram Eldar, Dec 15 2022

Keywords

• nonn
• base

Comments

All the terms are odd since A246600(2*k) = A246600(k).

Links

• Amiram Eldar, Table of n, a(n) for n = 1..142
• Index entries for sequences related to binary expansion of n.
• Index entries for sequences related to divisors of numbers.

Crossrefs

Cf. A000005, A046801, A246600, A359080, A359082, A359083.

Programs

Mathematica

seq[nmax_, kmax_] := Module[{s = Table[0, {nmax}], c = 0, k = 1, i}, While[c < nmax && k < kmax, i = DivisorSum[k, 1 &, BitOr[#, k] == k &]; If[i <= nmax && s[[i]] == 0, c++; s[[i]] = k]; k++]; s]; seq[20, 5*10^6]

PARI

lista(nmax, kmax=oo) = {my(s = vector(nmax), c = 0, k = 1, i); while(c < nmax && k < kmax, i = sumdiv(k, d, bitor(d, k) == k); if(i <= nmax && s[i] == 0, c++; s[i] = k); k++); s};