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A201131 Least k such that (5^n - k)*5^n + 1 is a prime number. 1
3, 1, 11, 1, 5, 19, 9, 1, 11, 15, 9, 69, 27, 21, 77, 85, 53, 1, 5, 201, 9, 43, 93, 403, 45, 87, 17, 63, 45, 15, 23, 9, 17, 273, 51, 31, 111, 277, 45, 39, 51, 229, 9, 109, 29, 357, 81, 1, 237, 33, 137, 169, 137, 847, 75, 367, 57, 87, 285, 25, 105, 177, 113, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..64.

MATHEMATICA

Table[k = 0; While[!PrimeQ[(5^n - k)*5^n + 1], k++]; k, {n, 85}]

CROSSREFS

Cf. A200923, A200923.

Sequence in context: A200652 A276391 A119632 * A277790 A134761 A166752

Adjacent sequences:  A201128 A201129 A201130 * A201132 A201133 A201134

KEYWORD

nonn

AUTHOR

Michel Lagneau, Nov 27 2011

STATUS

approved

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Last modified November 13 19:25 EST 2018. Contains 317149 sequences. (Running on oeis4.)