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 A163294 a(n) = 2 + Sum_{x=n..prime(n)} (-x*(-1)^x). 1
 1, 3, 6, 4, 10, 6, 14, 8, 18, 12, 23, 15, 29, 17, 33, 21, 40, 24, 45, 28, 49, 31, 55, 35, 63, 40, 67, 42, 71, 44, 81, 52, 87, 55, 94, 60, 99, 65, 105, 69, 112, 72, 119, 77, 123, 79, 131, 90, 140, 92, 144, 96, 149, 101, 158, 106, 165, 109, 170, 113, 174, 118, 187, 126, 191 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS G. C. Greubel, Table of n, a(n) for n = 1..1000 EXAMPLE a(1) = 2 + 1 - 2 = 1; a(2) = 2 - 2 + 3 = 3; a(3) = 2 + 3 - 4 + 5 = 6; a(4) = 2 - 4 + 5 - 6 + 7 = 4; a(5) = 2 + 5 - 6 + 7 - 8 + 9 - 10 + 11 = 10. MAPLE A163294 := proc(n) 2+add( -j*(-1)^j, j=n..ithprime(n)) ; end: seq(A163294(n), n=1..120) ; # R. J. Mathar, Oct 10 2009 MATHEMATICA Table[2 + Sum[k*(-1)^(k + 1), {k, n, Prime[n]}], {n, 1, 100}] (* G. C. Greubel, Dec 17 2016 *) PROG (PARI) for(n=1, 50, print1(2 + sum(k=n, prime(n), k*(-1)^(k+1)), ", ")) \\ G. C. Greubel, Dec 17 2016 CROSSREFS Cf. A000027, A000040. Sequence in context: A242224 A294671 A275985 * A168577 A122634 A169846 Adjacent sequences:  A163291 A163292 A163293 * A163295 A163296 A163297 KEYWORD nonn,less AUTHOR Juri-Stepan Gerasimov, Jul 24 2009 EXTENSIONS Corrected by Juri-Stepan Gerasimov, Jul 26 2009 Edited (but not checked) by N. J. A. Sloane, Jul 27 2009 Roughly 50 percent of the entries corrected by R. J. Mathar, Oct 10 2009 STATUS approved

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Last modified December 15 20:00 EST 2019. Contains 330000 sequences. (Running on oeis4.)