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 A048859 A sieve: keep the first 2 numbers, delete the next 3 numbers; keep the next 3 numbers, delete the next 4 numbers; keep the next 4 numbers, delete the next 5 numbers; and so on. In other words, keep the next k numbers and delete the next k+1 numbers, for k = 2, 3, ... 5
 1, 2, 6, 7, 8, 13, 14, 15, 16, 22, 23, 24, 25, 26, 33, 34, 35, 36, 37, 38, 46, 47, 48, 49, 50, 51, 52, 61, 62, 63, 64, 65, 66, 67, 68, 78, 79, 80, 81, 82, 83, 84, 85, 86, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES C. Dumitrescu & V. Seleacu, editors, Some Notions and Questions in Number Theory, Vol. I, Erhus Publ., Glendale, 1994. M. Le, On the Smarandache n-ary Sieve, Smarandache Notions Journal, Vol. 10, No. 1-2-3, 1999, 146-147. F. Smarandache, Properties of Numbers, 1972. LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 C. Dumitrescu & V. Seleacu, editors, Some Notions and Questions in Number Theory, Vol. I. EXAMPLE List the natural numbers: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, ... Keep the first two numbers 1, 2 and delete the next three numbers 3, 4, 5. Keep the next three numbers 6, 7, 8 and delete the next four numbers 9, 10, 11, 12. And so on. MATHEMATICA ss[n_]:=Module[{c=n^2+4n+1}, Range[c, c+n+1]]; Flatten[Array[ss, 10, 0]] (* Harvey P. Dale, Sep 10 2014 *) PROG (Haskell) a048859 n = a048859_list !! (n-1) a048859_list = f 2 [1..] where    f k xs = us ++ f (k + 1) (drop (k + 1) vs)             where (us, vs) = splitAt k xs -- Reinhard Zumkeller, May 16 2014 CROSSREFS Cf. A007950, A007951, A007952. Cf. A064801. Sequence in context: A285160 A287321 A030366 * A026311 A063291 A088225 Adjacent sequences:  A048856 A048857 A048858 * A048860 A048861 A048862 KEYWORD nonn AUTHOR Charles T. Le (charlestle(AT)yahoo.com) EXTENSIONS Corrected and revised by the author, Mar 24 2004 More terms from Bernardo Boncompagni Jul 27 2004 Offset changed by Reinhard Zumkeller, May 16 2014 STATUS approved

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Last modified September 28 10:48 EDT 2021. Contains 347714 sequences. (Running on oeis4.)