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A339567
Numbers k such that A007088(k) == 1 (mod k).
2
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.
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
Sequence in context: A147495 A147426 A100437 * A067533 A110343 A146060
KEYWORD
nonn,base
AUTHOR
Robert Israel, Dec 09 2020
EXTENSIONS
a(30)-a(34) from Daniel Suteu, Dec 12 2020
STATUS
approved