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Search: id:A113304
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| A113304 |
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Primes that divide some central trinomial coefficient, A002426. |
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+0
4
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| 3, 7, 17, 19, 41, 43, 47, 73, 107, 109, 113, 131, 173, 179, 191, 193, 199, 233, 269, 277, 281, 283, 293, 307, 311, 347, 373, 383, 401, 409, 419, 421, 439, 443, 457, 467, 503, 509, 521, 547, 563, 569, 593, 613, 617, 631, 653, 673, 691, 701, 709, 719, 739, 743
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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For primes less than 10^6, the density of these primes is near 0.3925.
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MATHEMATICA
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nn=1000; a=b=1; t=Join[{1}, Table[c=((2n-1)b+3(n-1)a)/n; a=b; b=c; c, {n, 2, nn}]]; pLst={}; Do[p=Prime[n]; k=1; While[k<p && Mod[t[[k]], p]>0, k++ ]; If[k<p, AppendTo[pLst, p]], {n, PrimePi[nn]}]; pLst
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CROSSREFS
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Cf. A113302 (number of k for which prime(n) divides T(k)), A113303 (least k such that prime(n) divides T(k)).
Sequence in context: A140863 A076194 A064699 this_sequence A093651 A018411 A083989
Adjacent sequences: A113301 A113302 A113303 this_sequence A113305 A113306 A113307
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KEYWORD
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nonn
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AUTHOR
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T. D. Noe (noe(AT)sspectra.com), Oct 24 2005
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