

A277370


Positive integers k that divide 7^k + 2.


6



1, 3, 15, 69, 2155, 34073, 876047637, 97090036327, 420397381695, 2125899832395, 3177544777277, 34434175473881, 40845965389135
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OFFSET

1,2


COMMENTS

All terms are odd.
No other terms below 10^15. Some larger terms: 21419515204636141, 5623143546839445899891, 46186634668308298262543001.  Max Alekseyev, Oct 18 2016


LINKS

Table of n, a(n) for n=1..13.


FORMULA

A066438(a(n)) = a(n)  2 for n > 1.


EXAMPLE

7^3 + 2 = 345 = 3 * 115, so 3 is a term.


MATHEMATICA

Select[Range[1, 9999, 2], Divisible[7^# + 2, #] &] (* Alonso del Arte, Oct 11 2016 *)


PROG

(PARI) is(n) = Mod(7, n)^n==2 \\ Felix Fröhlich, Oct 14 2016


CROSSREFS

Cf. A066438.
Cf. Solutions to 7^n == k (mod n): A277371 (k=3), this sequence (k=2), A015954 (k=1), A067947 (k=1), A277401 (k=2), A277554 (k=3).
Sequence in context: A110211 A167874 A318967 * A213140 A245751 A033876
Adjacent sequences: A277367 A277368 A277369 * A277371 A277372 A277373


KEYWORD

nonn,more


AUTHOR

Seiichi Manyama, Oct 11 2016


EXTENSIONS

a(8)a(13) from Max Alekseyev, Oct 18 2016


STATUS

approved



