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 A072592 Even numbers with at least one prime factor of form 4*k+1. 3
 10, 20, 26, 30, 34, 40, 50, 52, 58, 60, 68, 70, 74, 78, 80, 82, 90, 100, 102, 104, 106, 110, 116, 120, 122, 130, 136, 140, 146, 148, 150, 156, 160, 164, 170, 174, 178, 180, 182, 190, 194, 200, 202, 204, 208, 210, 212, 218, 220, 222, 226, 230, 232, 234, 238 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A072591(a(n)) = 0. Conjecture: this is exactly the sequence whose terms are twice those of A009003. (This has been verified for all terms<=500.) Compare A009003. - John W. Layman, Mar 12 2008 The conjecture is true. See comments on A008846 and A004613. - Lambert Herrgesell (zero815(AT)googlemail.com), Apr 24 2008 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 MATHEMATICA opfQ[n_]:=Count[Transpose[FactorInteger[n]][[1]], _?(IntegerQ[ (#-1)/4]&)]>0; Select[Range[2, 250, 2], opfQ] (* Harvey P. Dale, Jun 02 2012 *) CROSSREFS Cf. A005843, A002144. Sequence in context: A342142 A179819 A320522 * A229305 A229304 A101869 Adjacent sequences:  A072589 A072590 A072591 * A072593 A072594 A072595 KEYWORD nonn AUTHOR Reinhard Zumkeller, Jun 23 2002 STATUS approved

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Last modified November 27 02:53 EST 2021. Contains 349344 sequences. (Running on oeis4.)