A102646 Numbers of form j k^2 with 1 <= j <= k, gcd(j,k) = 1.

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

Offset: 1

Author

Leroy Quet, Feb 25 2005

Keywords

• nonn

Comments

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

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

Examples

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

Links

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

Crossrefs

Cf. A102448.

Programs

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

Extensions

Edited by David W. Wilson, Sep 03 2005