A306294 Least inverse of A162961.

1, 2, 3, 4, 5, 14, 7, 8, 9, 22, 11, 26, 13, 35, 40, 16, 17, 38, 19, 132, 77, 46, 23, 50, 25, 54, 27, 58, 29, 62, 31, 32, 187, 85, 370, 74, 37, 247, 104, 82, 41, 86, 43, 99, 115, 94, 47, 98, 49, 300, 221, 106, 53, 135, 380, 133, 354, 118, 59, 122, 61, 217, 144, 64

Offset

1,2

Comments

Is this sequence a permutation of the positive integers? (Equivalently, does A162961 take every positive integer as a value?)

Links

Michel Marcus, Table of n, a(n) for n = 1..1000

Formula

a(n) = min{k : A162961(k) = n}.

a(p^k) = p^k for all prime powers p^k, and a(p^k-1) = 2*p^k for p^k an odd prime power that is not a Fermat prime or 9.

Prog

(PARI) isokp(m, perm, f, nb) = {for (k=1, nb, if ((m+k-1) % f[perm[k], 1]^f[perm[k], 2], return (0)); ); return (1); }
isokm(m, f, nb) = {for (j=0, nb!-1, my(perm = numtoperm(nb, j)); if (isokp(m, perm, f, nb), return (1)); ); return (0); }
a162961(n) = {my(f = factor(n), nb = #f~, m = 1); while (! isokm(m, f, nb), m++); m; }
a(n) = {my(k=1); while (a162961(k) != n, k++); k; } \\ Michel Marcus, Feb 05 2019

Crossrefs

Cf. A162961, A000961.

Sequence in context: A175303 A057158 A138986 * A098552 A245447 A361947

Adjacent sequences: A306291 A306292 A306293 * A306295 A306296 A306297

Keyword

nonn

Author

Charlie Neder, Feb 04 2019

Status

approved