A166743 a(n) = (2^p - p^2 - 1)/6 where p = prime(n).

1, 13, 321, 1337, 21797, 87321, 1398013, 89478345, 357913781, 22906492017, 366503875645, 1466015503393, 23456248058853, 1501199875789697, 96076792050570001, 384307168202281705, 24595658764946068073

Offset

3,2

Links

Harvey P. Dale, Table of n, a(n) for n = 3..468

Formula

a(n) = (A034785(n) - A066872(n))/6. - R. J. Mathar, Oct 25 2009

Maple

A166743 := proc(n) p := ithprime(n) ; (2^p-p^2-1)/6 ; end: seq(A166743(n), n=3..20) ; # R. J. Mathar, Oct 25 2009

Mathematica

Table[(2^p-p^2-1)/6, {p, Prime[Range[3, 20]]}] (* Harvey P. Dale, May 16 2020 *)

Crossrefs

Cf. A034785, A066872.

Sequence in context: A305143 A132485 A297437 * A212733 A183803 A253458

Adjacent sequences: A166740 A166741 A166742 * A166744 A166745 A166746

Keyword

nonn

Author

Tanin (Mirza Sabbir Hossain Beg) (mirzasabbirhossainbeg(AT)yahoo.com), Oct 21 2009

Extensions

Missing exponentiation signs inserted in the definition by R. J. Mathar, Oct 25 2009

Corrected by D. S. McNeil, Aug 20 2010

Status

approved