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 A125241 Numbers k such that binomial(4k, k) + 1 is prime. 5
 0, 1, 2, 6, 10, 11, 19, 28, 80, 123, 141, 147, 154, 198, 200, 346, 851, 887, 1038, 1329, 2045, 3228, 3274, 3588, 6794, 8045, 11911, 12184, 12327, 12515, 20089, 38173, 41026, 48914 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS MATHEMATICA Do[f=Binomial[4n, n]+1; If[PrimeQ[f], Print[n]], {n, 1, 1000}] Select[Range[8100], PrimeQ[Binomial[4#, #]+1]&] (* Harvey P. Dale, Aug 24 2014 *) CROSSREFS Cf. A125240 = 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: A225271 A050425 A030405 * A116043 A085258 A133520 Adjacent sequences:  A125238 A125239 A125240 * A125242 A125243 A125244 KEYWORD hard,more,nonn AUTHOR Alexander Adamchuk, Nov 25 2006 EXTENSIONS More terms from Ryan Propper, Mar 28 2007 a(1)=0 added by Robert Price, May 01 2019 a(27)-a(34) from Robert Price, May 01 2019 STATUS approved

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Last modified September 20 04:04 EDT 2020. Contains 337264 sequences. (Running on oeis4.)