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A308553 Numbers k such that 5^(k+3) + 3^(k+2) + 2^(k+1) + 1 is prime. 0
0, 4, 8, 524, 972, 3780, 7704 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Larger k values yield probable primes.

a(8) > 50000 (if it exists).

REFERENCES

Cf. A306573.

LINKS

Table of n, a(n) for n=1..7.

MATHEMATICA

ParallelTable[If[PrimeQ[5^(n+3) + 3^(n+2) + 2^(n+1) + 1], n, Nothing], {n, 0, 10^4}]

CROSSREFS

Sequence in context: A012994 A136386 A260726 * A177860 A013443 A013442

Adjacent sequences:  A308550 A308551 A308552 * A308554 A308555 A308556

KEYWORD

nonn,hard,more

AUTHOR

Mikk Heidemaa, Jun 07 2019

STATUS

approved

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Last modified October 23 16:46 EDT 2019. Contains 328373 sequences. (Running on oeis4.)