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A140210 a(n) = Product_{h == 1 (mod 4) and h|n} h. 3
1, 1, 1, 1, 5, 1, 1, 1, 9, 5, 1, 1, 13, 1, 5, 1, 17, 9, 1, 5, 21, 1, 1, 1, 125, 13, 9, 1, 29, 5, 1, 1, 33, 17, 5, 9, 37, 1, 13, 5, 41, 21, 1, 1, 2025, 1, 1, 1, 49, 125, 17, 13, 53, 9, 5, 1, 57, 29, 1, 5, 61, 1, 189, 1, 4225, 33, 1, 17, 69, 5, 1, 9, 73, 37, 125, 1, 77, 13, 1, 5, 729, 41, 1, 21 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..10000

MAPLE

with(numtheory):

a:= n-> mul(i, i=select(h-> irem(h, 4)=1, divisors(n))):

seq(a(n), n=1..120);  # Alois P. Heinz, Jul 28 2009

MATHEMATICA

a[n_] := Times @@ Select[Divisors[n], Mod[#, 4] == 1&]; Table[a[n], {n, 1, 120}] (* Jean-Fran├žois Alcover, Jun 24 2015 *)

PROG

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

CROSSREFS

Cf. A007955, A140211, A136655, A140213, A140214, A140215, A136655.

Sequence in context: A322837 A168677 A345939 * A010130 A206773 A229526

Adjacent sequences:  A140207 A140208 A140209 * A140211 A140212 A140213

KEYWORD

nonn,look

AUTHOR

R. J. Mathar, Jun 27 2008

EXTENSIONS

More terms from Alois P. Heinz, Jul 28 2009

STATUS

approved

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Last modified October 22 21:23 EDT 2021. Contains 348180 sequences. (Running on oeis4.)