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 A184939 From the base sequence of the positive integers, keep the first two, remove the next three, keep the next five, remove the next seven, ..., block lengths determined by the prime numbers. 1
 1, 2, 6, 7, 8, 9, 10, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 130, 131, 132 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Accept 1st prime, reject 2nd prime, accept 3rd prime, reject 4th prime, ... starting with natural numbers A000027. First string of consecutive values ends with 2, second such string ends with 10 = 2+3+5, 3rd such string ends with 28 = 2+3+5+7+11, namely A007504(2k+1). LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 EXAMPLE In parentheses the blocks of integers removed: 1 2 (3 4 5) 6 7 8 9 10 (11 12 13 14 15 16 17) 18 19 20 21 22 23 24 25 26 27 28 (29 30 ...). MAPLE L := [] ; p := 2 ; ptr := 1 ; while p < 40 do         L := [op(L), seq(j, j=ptr..ptr+p-1)] ; ptr := ptr+p ; p := nextprime(p) ;         ptr := ptr+p ; p := nextprime(p) ; end do: L ; # R. J. Mathar, Feb 08 2011 MATHEMATICA Module[{nn=20, t}, t=Total[Prime[Range[nn]]]; Take[TakeList[Range[t], Prime[ Range[nn]]], {1, nn, 2}]]//Flatten (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 04 2019 *) CROSSREFS Cf. A000040, A004201, A007504. Sequence in context: A073005 A091942 A047555 * A043050 A159843 A243652 Adjacent sequences:  A184936 A184937 A184938 * A184940 A184941 A184942 KEYWORD nonn,easy AUTHOR Jonathan Vos Post, Feb 02 2011 STATUS approved

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Last modified June 22 12:42 EDT 2021. Contains 345379 sequences. (Running on oeis4.)