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A072437
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Numbers with no prime factors of form 4*k+3.
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11
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1, 2, 4, 5, 8, 10, 13, 16, 17, 20, 25, 26, 29, 32, 34, 37, 40, 41, 50, 52, 53, 58, 61, 64, 65, 68, 73, 74, 80, 82, 85, 89, 97, 100, 101, 104, 106, 109, 113, 116, 122, 125, 128, 130, 136, 137, 145, 146, 148, 149, 157, 160, 164, 169, 170, 173, 178, 181, 185, 193, 194
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graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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m is a term iff A072436(m) = m.
These numbers have density zero (Pollack).
A005091(a(n)) = 0. - Reinhard Zumkeller, Jan 07 2013
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LINKS
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Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
P. Pollack, Analytic and Combinatorial Number Theory Course Notes, p. 119. alternate link
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FORMULA
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n>0 such that A001842(n)=0. - Benoit Cloitre, Apr 24 2003
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MATHEMATICA
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npfQ[n_]:=Count[Transpose[FactorInteger[n]][[1]], _?(Mod[#, 4]==3&)]==0; Select[Range[200], npfQ] (* Harvey P. Dale, Nov 12 2013 *)
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PROG
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(PARI) is(n)=n==1||vecmax(factor(n)[, 1]%4)<3 \\ Charles R Greathouse IV, Apr 16 2012
(Haskell)
import Data.List (elemIndices)
a072437 n = a072437_list !! (n-1)
a072437_list = map (+ 1) $ elemIndices 0 a005091_list
-- Reinhard Zumkeller, Jan 07 2013
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CROSSREFS
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Cf. A004144, A002144, A002145.
A097706(a(n)) = 1.
Cf. A187811 (complement).
Sequence in context: A268381 A186349 A304360 * A115793 A076614 A227800
Adjacent sequences: A072434 A072435 A072436 * A072438 A072439 A072440
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller, Jun 17 2002
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STATUS
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approved
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