A062671 Every divisor (except 1) contains the digit 5.

5, 25, 53, 59, 125, 151, 157, 251, 257, 265, 295, 353, 359, 457, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 625, 653, 659, 751, 755, 757, 785, 853, 857, 859, 953, 1051, 1151, 1153, 1255, 1259, 1285, 1325, 1451, 1453, 1459, 1475, 1511

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

25 has divisors 1, 5 and 25, all of which (except 1) contain the digit 5.

Mathematica

fQ[n_, dgt_] := Union[ MemberQ[#, dgt] & /@ IntegerDigits@ Rest@ Divisors@ n][[1]]; Select[ Range[2, 1500], fQ[#, 5] &] (* Robert G. Wilson v, Jun 11 2014 *)

Prog

(Magma) [k:k in [2..1500]| forall{d:d in Set(Divisors(k)) diff {1}| 5 in Intseq(d)}]; // Marius A. Burtea, Nov 07 2019
(Python)
from sympy import divisors
def ok(n): return all('5' in str(d) for d in divisors(n)[1:])
print(list(filter(ok, range(2, 1512)))) # Michael S. Branicky, May 25 2021

Crossrefs

Cf. A062653, A062664, A062667, A062668, A062669, A062670, A062672, A062673, A062674, A062675, A062676, A062677, A062678, A062679, A062680.

Sequence in context: A043106 A147184 A036133 * A225494 A139479 A078569

Adjacent sequences: A062668 A062669 A062670 * A062672 A062673 A062674

Keyword

base,easy,nonn

Author

Erich Friedman, Jul 04 2001

Extensions

Offset corrected by Amiram Eldar, Nov 07 2019

Status

approved