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A109903
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Let c = composite(n) & p = prime(n); a(n) = binomial( max(c,p), min(c,p) ).
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6, 20, 56, 36, 11, 13, 680, 3876, 245157, 34597290, 84672315, 12875774670, 244662670200, 800472431850, 14833897694226, 973469712824056, 48402641245296107, 191724747789809255, 9989690752182277136
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| 11 and 13 are the only prime terms. For a(7) onwards sequence is monotonically increasing.
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EXAMPLE
| a(3) = C(8,5) = 56, a(8) = C(19,15) =3876.
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MATHEMATICA
| Composite[ n_Integer ] := Block[{k = n + PrimePi[ n ] + 1}, While[ k != n + PrimePi[ k ] + 1, k++ ]; k]; f[n_] := Block[{a = Sort[{Composite[n], Prime[n]}]}, Binomial[Last[a], First[a]]]; Table[ f[n], {n, 19}] (from Robert G. Wilson v (rgwv(at)rgwv.com), Jul 16 2005)
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CROSSREFS
| Sequence in context: A028492 A059822 A152959 * A201149 A014480 A048778
Adjacent sequences: A109900 A109901 A109902 * A109904 A109905 A109906
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KEYWORD
| easy,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jul 14 2005
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(at)rgwv.com), Jul 16 2005
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