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 A166743 a(n) = (2^p - p^2 - 1)/6 where p = prime(n). 1
 1, 13, 321, 1337, 21797, 87321, 1398013, 89478345, 357913781, 22906492017, 366503875645, 1466015503393, 23456248058853, 1501199875789697, 96076792050570001, 384307168202281705, 24595658764946068073 (list; graph; refs; listen; history; text; internal format)
 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

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Last modified January 19 06:28 EST 2021. Contains 340266 sequences. (Running on oeis4.)