A271627 Numbers n such that the sum of the digits of the numbers from 1 to n is a prime.

2, 16, 22, 25, 61, 118, 133, 193, 217, 226, 232, 262, 265, 286, 310, 337, 358, 397, 433, 445, 466, 496, 508, 538, 553, 565, 580, 613, 652, 697, 718, 733, 745, 757, 781, 790, 856, 901, 958, 985, 988, 1021, 1093, 1186, 1201, 1210, 1258, 1273, 1285, 1297, 1312, 1321

Offset

1,1

Links

Paolo P. Lava, Table of n, a(n) for n = 1..10000

Example

1 + 2 = 3 that is a prime; 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 1 + 0 + 1 + 1 + 1 + 2 + 1 + 3 + 1 + 4 + 1 + 5 + 1 + 6 = 73 that is a prime.

Maple

with(numtheory): P:=proc(q) local a, b, c, k, n; a:=0;
for n from 1 to q do b:=0; c:=n; for k from 1 to ilog10(n)+1 do b:=b+(c mod 10); c:=trunc(c/10); od; a:=a+b;
if isprime(a) then print(n); fi; od; end: P(10^4);

Mathematica

Select[Range@ 1350, PrimeQ@ Total@ Map[Total@ IntegerDigits@ # &, Range@ #] &] (* Michael De Vlieger, Apr 11 2016 *)

Prog

(PARI) isok(n) = isprime(sum(k=1, n, sumdigits(k))); \\ Michel Marcus, Apr 11 2016

Crossrefs

Cf. A000040, A037123.

Sequence in context: A333998 A081767 A093026 * A118954 A119599 A333475

Adjacent sequences: A271624 A271625 A271626 * A271628 A271629 A271630

Keyword

nonn,easy,base

Author

Paolo P. Lava, Apr 11 2016

Status

approved