login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

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