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A127315 Numbers n such that n^4 divides 19^(n^2)-1. 0
1, 2, 3, 6, 42, 78, 546, 1806, 23478 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n)^2 are the perfect squares in A128399.

a(10) > 10^13. [From Max Alekseyev]

LINKS

Table of n, a(n) for n=1..9.

MATHEMATICA

Do[g=PowerMod[19, n^2, n^4]-1; If[IntegerQ[g/n^4], Print[n]], {n, 1, 10000}]

CROSSREFS

Cf. A128399 = numbers n such that n^2 divides 19^n-1.

Sequence in context: A184716 A018354 A124045 * A018359 A274805 A049383

Adjacent sequences:  A127312 A127313 A127314 * A127316 A127317 A127318

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk, Mar 28 2007

EXTENSIONS

a(9) from D. S. McNeil, Mar 02 2009

STATUS

approved

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Last modified December 12 12:50 EST 2019. Contains 329958 sequences. (Running on oeis4.)