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A170817 a(n) = product of distinct primes of form 4k+1 that divide n. 4
1, 1, 1, 1, 5, 1, 1, 1, 1, 5, 1, 1, 13, 1, 5, 1, 17, 1, 1, 5, 1, 1, 1, 1, 5, 13, 1, 1, 29, 5, 1, 1, 1, 17, 5, 1, 37, 1, 13, 5, 41, 1, 1, 1, 5, 1, 1, 1, 1, 5, 17, 13, 53, 1, 5, 1, 1, 29, 1, 5, 61, 1, 1, 1, 65, 1, 1, 17, 1, 5, 1, 1, 73, 37, 5, 1, 1, 13, 1, 5, 1, 41, 1, 1, 85, 1, 29, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MAPLE

a:= n-> mul (i, i=map (x-> x[1], select (x-> isprime (x[1]) and irem (x[1], 4)=1, ifactors(n)[2]))): seq (a(n), n=1..120);

MATHEMATICA

Table[Times@@Select[Transpose[FactorInteger[n]][[1]], Mod[#, 4]==1&], {n, 90}] (* Harvey P. Dale, Dec 07 2012 *)

CROSSREFS

Cf. A170818-A170819, A097706, A083025, A170824, A170825.

Sequence in context: A109009 A060904 A135469 * A170818 A046622 A170825

Adjacent sequences:  A170814 A170815 A170816 * A170818 A170819 A170820

KEYWORD

nonn,mult

AUTHOR

N. J. A. Sloane, Dec 22 2009

EXTENSIONS

Corrected and extended with Maple program by Alois P. Heinz, Dec 23 2009

STATUS

approved

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Last modified December 12 16:18 EST 2017. Contains 295939 sequences.