A339567 Numbers k such that A007088(k) == 1 (mod k).

1, 5, 15, 25, 55, 91, 137, 525, 625, 925, 3967, 5995, 7625, 10767, 25087, 57225, 68817, 565027, 591415, 2515825, 2757625, 4162019, 5276309, 96689255, 115686005, 133890625, 242899421, 492029715, 588620625, 1839399055, 7786281065, 11231388063, 17251448809, 71050380625

Offset

1,2

Comments

All terms are odd.

Links

Table of n, a(n) for n=1..34.

Example

a(3) = 15 is a term because 15 = 1111_2 and 1111 == 1 (mod 15).

Maple

filter:= t -> convert(t, binary) mod t = 1: filter(1):= true:
select(filter, [seq(i, i=1..10^7, 2)]);

Mathematica

Block[{a = {1}, k}, Do[If[Mod[FromDigits@ IntegerDigits[i, 2], i] == 1, AppendTo[a, i]], {i, 2, 10^7}]; a] (* Michael De Vlieger, Dec 12 2020 *)

Prog

(PARI) isok(n) = Mod(fromdigits(binary(n)), n) == 1;
forstep(k=1, 10^7, 2, if(isok(k), print1(k, ", "))); \\ Daniel Suteu, Dec 12 2020

Crossrefs

Cf. A007088, A339566.

Sequence in context: A147495 A147426 A100437 * A067533 A110343 A146060

Adjacent sequences: A339564 A339565 A339566 * A339568 A339569 A339570

Keyword

nonn,base

Author

Robert Israel, Dec 09 2020

Extensions

a(30)-a(34) from Daniel Suteu, Dec 12 2020

Status

approved