A283565 Numbers n such that n = Sum_{k=1..m} (n mod k) for some m.

0, 1, 2, 7, 8, 9, 10, 13, 15, 19, 22, 23, 25, 31, 37, 49, 51, 52, 57, 72, 95, 98, 100, 133, 140, 146, 152, 158, 168, 189, 196, 212, 315, 348, 376, 383, 396, 407, 416, 451, 452, 497, 521, 541, 548, 551, 568, 583, 586, 592, 593, 657, 663, 683, 729, 780, 784, 794

Offset: 1

Author

Rémy Sigrist, Mar 11 2017

Keywords

• nonn

Comments

A283593 gives the least m > 0 as described in the name.

Numbers t such that t and 2*t are both in this sequence are 0, 1, 49, 98, 1249, 2599, 3784, 9565, 10933, ... - Altug Alkan, Mar 11 2017

Examples

			(7 mod 1) + (7 mod 2) + (7 mod 3) + (7 mod 4) + (7 mod 5) = 0 + 1 + 1 + 3 + 2 = 7, hence 7 appears in this sequence.
(4 mod 1) + (4 mod 2) + (4 mod 3) + (4 mod 4) = 0 + 0 + 1 + 0 = 1, and (4 mod 1) + (4 mod 2) + (4 mod 3) + (4 mod 4) + (4 mod 5) = 0 + 0 + 1 + 0 + 4 = 5, hence 4 does not appear in this sequence.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A004125, A283593.

Programs

PARI

isok(n) = my (s=0); my (k=1); while (s