A369969 Numbers that are not multiples of 5, but their arithmetic derivative is.

1, 6, 21, 26, 32, 36, 46, 51, 76, 86, 88, 91, 99, 106, 111, 112, 116, 126, 141, 146, 156, 161, 166, 192, 201, 206, 209, 216, 221, 226, 236, 242, 243, 248, 266, 272, 276, 279, 291, 301, 306, 308, 316, 319, 321, 326, 328, 346, 356, 369, 371, 381, 386, 391, 392, 406, 411, 429, 436, 441, 446, 456, 466, 471, 481, 488, 501

Offset

1,2

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

filter:= proc(n) local F, np, t;
  if n mod 5 = 0 then return false fi;
  F:= ifactors(n)[2];
  np:= add(n*t[2]/t[1], t=F);
  np mod 5 = 0
end proc:
select(filter, [$1..1000]); # Robert Israel, Dec 05 2024

Prog

(PARI) \\ See A369968.

Crossrefs

Intersection of A047201 and A327865.

Includes A050997 \ {3125} as a subsequence.

Cf. A003415, A369968 (characteristic function).

Cf. also A046337, A369659, A360110 for cases k=2, 3, 4 of "Nonmultiples of k whose arithmetic derivative is a multiple of k".

Sequence in context: A364202 A323917 A327865 * A229498 A164698 A020880

Adjacent sequences: A369966 A369967 A369968 * A369970 A369971 A369972

Keyword

nonn

Author

Antti Karttunen, Feb 10 2024

Status

approved