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A273403 Numbers n such that (10^n - 7^n)/3 is prime. 0
2, 31, 103, 617, 10253, 10691 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are prime.

The corresponding primes: 17, 3333280741539321718064461652419, ...

LINKS

Table of n, a(n) for n=1..6.

MATHEMATICA

Select[Range[1, 10000], PrimeQ[(10^# - 7^#)/3] &]

PROG

(PARI) for(n=1, 10000, if(isprime((10^n - 7^n)/3), print1(n, ", ")))

CROSSREFS

Cf. A004023, A128026, A062576.

Sequence in context: A101254 A243472 A107170 * A291052 A267888 A229014

Adjacent sequences:  A273400 A273401 A273402 * A273404 A273405 A273406

KEYWORD

nonn,more,hard

AUTHOR

Tim Johannes Ohrtmann, May 21 2016

STATUS

approved

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Last modified May 22 00:25 EDT 2019. Contains 323472 sequences. (Running on oeis4.)