A125240 - OEIS

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A125240

Numbers k such that binomial(4k, k) - 1 is prime.

1, 16, 36, 67, 95, 369, 383, 745, 1599, 2006, 2104, 2879, 3061, 9048, 9902, 12369, 15058, 18858, 21287, 22759, 24674, 33899, 43730, 55078, 86085

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OFFSET

1,2

COMMENTS

a(26) > 10^5 - Robert Price, Sep 15 2024

LINKS

Table of n, a(n) for n=1..25.

MATHEMATICA

Do[f=Binomial[4n, n]-1; If[PrimeQ[f], Print[n]], {n, 1, 1000}]

CROSSREFS

Cf. A125241 = numbers n such that binomial(4n, n) + 1 is prime. Cf. A066699 = numbers n such that binomial(2n, n) + 1 is prime. Cf. A066726 = numbers n such that binomial(2n, n) - 1 is prime. Cf. A125220, A125221, A125242, A125243, A125244, A125245.

Sequence in context: A331139 A031360 A295016 * A050775 A022040 A074985

Adjacent sequences: A125237 A125238 A125239 * A125241 A125242 A125243

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk, Nov 25 2006

EXTENSIONS

More terms from Ryan Propper, Mar 28 2007

a(16)-a(23) from Robert Price, Apr 30 2019

a(24)-a(25) from Robert Price, Sep 15 2024

STATUS

approved