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A146510
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a(n) = numbers congruent to 1 or 4 modulo 5
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0
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1, 4, 16, 19, 31, 34, 46, 49, 61, 64, 76, 79, 91, 94, 106, 109, 121, 124, 136, 139, 151, 154, 166, 169, 181, 184, 196, 199, 211, 214, 226, 229, 241, 244, 256, 259, 271, 274, 286, 289, 301, 304, 316, 319, 331, 334, 346, 349, 361, 364, 376, 379, 391, 394, 406
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Positive integers k such that Hypergeometric[k/5,(5-k)/5,1/2,3/4] = 2Cos[Pi/5]
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FORMULA
| a(n)=5(s-1)+1 for n odd a(n)=5(s-1)+4 for n even
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MATHEMATICA
| aa = {}; Do[Do[k = 2 Pi/ ArcCos[Hypergeometric2F1[a/b, (b - a)/b, 1/2, 3/4]/2]; m = RootApproximant[N[k, 50], 1]; If[m == 10, AppendTo[aa, a]], {b, 5, 5}], {a, 1, 1000}]; Union[aa] (*Artur Jasinski*)
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CROSSREFS
| A146502-A146522
Sequence in context: A117102 A077476 A175527 * A032827 A071966 A039943
Adjacent sequences: A146507 A146508 A146509 * A146511 A146512 A146513
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KEYWORD
| nonn
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AUTHOR
| Artur Jasinski (grafix(AT)csl.pl), Oct 30 2008
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