A138850 Weird numbers (A006037) not divisible by 5.

836, 7192, 7912, 9272, 10792, 17272, 45356, 73616, 83312, 91388, 113072, 222952, 243892, 254012, 338572, 343876, 351956, 388076, 407132, 410476, 465652, 470668, 475684, 477356, 482372, 490732, 495748, 500764, 502436, 507452, 512468, 515812

Offset: 1

Author

M. F. Hasler, Apr 02 2008

Keywords

• nonn

Comments

Up to 200000, there are only 11 weird numbers not divisible by 5.

Since no A006037(k) < 10^17 is odd, at least up to there, "divisible by 5" is equivalent to "ending in 0" (in base 10).

It appears that 4*11*19*p is an element of this sequence for p=1 and all primes p>547. Moreover, these seem to comprise most of the terms of this sequence.

Up to n=500, the only indices for which a(n) is not of this form are n=2,...,16, 18, 34, 38, 43, 64, 83, 148, 158, 236, 266, 296, 310.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..500 from M. F. Hasler)

Crossrefs

Cf. A006037, A100696.

Programs

PARI

t=0; A138850=vector(50,i,until( (t+=2)%5 && is_A006037(t),);t) \\ [Updated by M. F. Hasler, Jan 07 2014]