A125244 - OEIS

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A125244

Numbers k such that binomial(6k, k) - 1 is prime.

1, 7, 17, 22, 43, 343, 381, 461, 543, 923, 1045, 1182, 1486, 1839, 5643, 8260, 9009, 10947, 11793, 15915, 25151

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OFFSET

1,2

COMMENTS

a(22) > 50000. - Robert Price, May 13 2019

LINKS

Table of n, a(n) for n=1..21.

MATHEMATICA

Do[f=Binomial[6n, n]-1; If[PrimeQ[f], Print[n]], {n, 1, 1000}]

CROSSREFS

Cf. A125245 = numbers n such that binomial(6n, 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, A125240, A125241, A125242, A125243.

Sequence in context: A053746 A327830 A144695 * A070416 A087168 A247560

Adjacent sequences: A125241 A125242 A125243 * A125245 A125246 A125247

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk, Nov 25 2006

EXTENSIONS

More terms from Ryan Propper, Mar 28 2007

a(18)-a(21) from Robert Price, May 13 2019

STATUS

approved