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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

Table of n, a(n) for n=3..19.

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

CROSSREFS

Sequence in context: A241022 A052114 A132485 * 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 - R. J. Mathar, Oct 25 2009

Corrected by D. S. McNeil, Aug 20 2010

STATUS

approved

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Last modified September 22 09:19 EDT 2017. Contains 292336 sequences.