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A156021 Numbers k such that k^1 + k^2 + k^3 + k^4 -+ 1 are twin primes. 3
1, 2, 12, 30, 44, 50, 63, 74, 110, 165, 177, 222, 239, 254, 327, 492, 519, 804, 942, 954, 1007, 1343, 1352, 1520, 1770, 2375, 2450, 2658, 2795, 2945, 2994, 3075, 3332, 3527, 3548, 3803, 3915, 3935, 4025, 4653, 4704, 4785, 4808, 4862, 5270, 5310, 5364, 5370 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

EXAMPLE

2 is a term since 2 + 2^2 + 2^3 + 2^4 - 1 = 29 and 2 + 2^2 + 2^3 + 2^4 + 1 = 31 are twin primes.

MATHEMATICA

lst={}; Do[p=(n^1+n^2+n^3+n^4); If[PrimeQ[p-1]&&PrimeQ[p+1], AppendTo[lst, n]], {n, 8!}]; lst

PROG

(MAGMA) [n: n in [1..6*10^3] | IsPrime(n^4+n^3+n^2+n-1) and IsPrime(n^4+n^3+n^2+n+1)]; // Vincenzo Librandi, Dec 26 2015

CROSSREFS

Cf. A125964, A156018.

Sequence in context: A215784 A061780 A249411 * A067348 A002939 A118239

Adjacent sequences:  A156018 A156019 A156020 * A156022 A156023 A156024

KEYWORD

nonn,easy

AUTHOR

Vladimir Joseph Stephan Orlovsky, Feb 01 2009

STATUS

approved

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Last modified January 26 15:18 EST 2022. Contains 350599 sequences. (Running on oeis4.)