A001007 a(n) = ( Sum C(p,i); i=1,...,floor(2p/3) ) / p^2, where p = prime(n).

1, 2, 15, 42, 421, 1331, 15119, 618765, 2155578, 98032875, 1290154807, 4682196239, 63117678751, 3186252107917, 164886529617695, 616630679090258, 32763760653353135, 467443761039641135, 1768227793278781667, 96699391743949360451, 1402535447576150395335

Offset

3,2

Links

T. D. Noe, Table of n, a(n) for n = 3..200

Mathematica

Table[p = Prime[n]; Sum[Binomial[p, i], {i, 1, Floor[2*p/3]}]/p^2, {n, 3, 30}] (* T. D. Noe, Jan 21 2013 *)

Crossrefs

Sequence in context: A249997 A032016 A254856 * A300393 A152015 A318914

Adjacent sequences: A001004 A001005 A001006 * A001008 A001009 A001010

Keyword

nonn

Author

R. K. Guy

Status

approved