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A073766 a(n) = binomial(composite(n+1), composite(n)) = binomial(A002808(n+1), A002808(n)). 2
15, 28, 9, 10, 66, 91, 15, 16, 153, 190, 21, 22, 276, 25, 26, 27, 28, 435, 496, 33, 34, 35, 36, 703, 39, 40, 861, 946, 45, 46, 1128, 49, 50, 51, 52, 1431, 55, 56, 57, 58, 1770, 1891, 63, 64, 65, 66, 2278, 69, 70, 2556, 2701, 75, 76, 77, 78, 3160, 81, 82, 3486, 85 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) equals either composite(n+1) or composite(w)+1 or binomial(c,2) for some composite number c.

LINKS

Michael De Vlieger, Table of n, a(n) for n = 1..10000

MATHEMATICA

Block[{f}, f[n_] := FixedPoint[n + PrimePi@ # + 1 &, n + PrimePi[n] + 1]; Array[Binomial[f[# + 1], f[#]] &, 10^4]] (* Michael De Vlieger, Nov 05 2020 *)

PROG

(PARI) lista(nn) = {my(prec  = 0); forcomposite(c=1, nn, if (prec, print1(binomial(c, prec), ", ")); prec = c; ); } \\ Michel Marcus, Mar 26 2020

CROSSREFS

Cf. A002808.

Sequence in context: A186074 A230649 A229195 * A223449 A031334 A178958

Adjacent sequences:  A073763 A073764 A073765 * A073767 A073768 A073769

KEYWORD

nonn

AUTHOR

Labos Elemer, Aug 09 2002

EXTENSIONS

Edited by Michael De Vlieger, Nov 05 2020

STATUS

approved

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Last modified September 24 22:46 EDT 2021. Contains 347651 sequences. (Running on oeis4.)