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A102646 Numbers of form j k^2 with 1 <= j <= k, gcd(j,k) = 1. 3
1, 4, 9, 16, 18, 25, 36, 48, 49, 50, 64, 75, 81, 98, 100, 121, 144, 147, 162, 169, 180, 192, 196, 225, 242, 245, 256, 289, 294, 300, 320, 324, 338, 361, 363, 400, 405, 441, 448, 450, 484, 507, 529, 567, 576, 578, 588, 605, 625, 648, 676, 700, 720, 722, 726, 729 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers n such that A102448(n) >= 1.

All positive squares x^2 are in the sequence with j = 1, k = x.

LINKS

David A. Corneth, Table of n, a(n) for n = 1..10000

EXAMPLE

180 is in the sequence with j = 5, k = 6.

PROG

(PARI) is(n) = {my(f = factor(n), podd = 1, peven = 1); for(i = 1, #f~, if(bittest(f[i, 2], 0), podd *= f[i, 1]^f[i, 2] , peven *= f[i, 1]^(f[i, 2] >> 1) ) ); podd <= peven } \\ David A. Corneth, Nov 11 2019

CROSSREFS

Cf. A102448.

Sequence in context: A104020 A066694 A235993 * A104021 A073804 A219364

Adjacent sequences:  A102643 A102644 A102645 * A102647 A102648 A102649

KEYWORD

nonn

AUTHOR

Leroy Quet, Feb 25 2005

EXTENSIONS

Edited by David W. Wilson, Sep 03 2005

STATUS

approved

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Last modified June 26 13:24 EDT 2022. Contains 354883 sequences. (Running on oeis4.)