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A140211 a(n) = Product_{d == 3 (mod 4) and d|n} d. 3
1, 1, 3, 1, 1, 3, 7, 1, 3, 1, 11, 3, 1, 7, 45, 1, 1, 3, 19, 1, 21, 11, 23, 3, 1, 1, 81, 7, 1, 45, 31, 1, 33, 1, 245, 3, 1, 19, 117, 1, 1, 21, 43, 11, 45, 23, 47, 3, 7, 1, 153, 1, 1, 81, 605, 7, 57, 1, 59, 45, 1, 31, 1323, 1, 1, 33, 67, 1, 69, 245, 71, 3, 1, 1, 3375, 19, 77, 117, 79, 1, 81, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

J. Mulder, Table of n, a(n) for n = 1..20000

FORMULA

a(n) | A007955(n). - R. J. Mathar, May 26 2016

MAPLE

A140211 := proc(n)

    a := 1;

    for d in numtheory[divisors](n) do

        if modp(d, 4) = 3 then

            a := a*d ;

        end if;

    end do:

    a;

end proc: # R. J. Mathar, Dec 15 2015

MATHEMATICA

ListProduct[lst_] := Fold[Times, 1, lst] lst = {}; For[n = 1, n <= 1000, n++, AppendTo[lst, ListProduct[Select[Divisors[n], Mod[ #, 4] == 3 &]]]] lst (* Jasper Mulder (jasper.mulder(AT)planet.nl), Jul 15 2009 *)

PROG

(PARI) a(n) = my(p=1); fordiv(n, d, if ((d % 4)==3, p*=d)); p; \\ Michel Marcus, Jan 07 2021

CROSSREFS

Cf. A140210, A007955.

Sequence in context: A107294 A161788 A170819 * A248101 A097706 A132740

Adjacent sequences:  A140208 A140209 A140210 * A140212 A140213 A140214

KEYWORD

nonn,easy

AUTHOR

R. J. Mathar, Jun 27 2008

STATUS

approved

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Last modified May 17 15:12 EDT 2021. Contains 343979 sequences. (Running on oeis4.)