A187101 Numbers whose largest proper divisor is a square.

8, 18, 27, 32, 50, 72, 75, 98, 125, 128, 147, 162, 200, 242, 243, 245, 288, 338, 343, 363, 392, 450, 507, 512, 578, 605, 648, 675, 722, 800, 845, 847, 867, 882, 968, 1058, 1083, 1152, 1183, 1250, 1323, 1331, 1352, 1445, 1458, 1568, 1587, 1682, 1800, 1805, 1859, 1875, 1922

Offset

1,1

Comments

Corresponding squares are: 4, 9, 9, 16, 25, 36, 25, 49, 25, 64, 49, 81, 100, 121, 81, 49, 144, 169, 49, 121, 196, ...

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

filter:= proc(n) not isprime(n) and issqr(n/min(numtheory:-factorset(n))) end proc:
select(filter, [$2..2000]); # Robert Israel, Jan 16 2020

Mathematica

Select[Range[2, 2000], !PrimeQ[#] && IntegerQ[Sqrt[Divisors[#][[-2]]]]&] (* Jean-François Alcover, Jul 17 2020 *)

Prog

(PARI) lista(m) = {for (n=2, m, d = divisors(n); lpd = d[length(d)-1]; if (lpd != 1 && issquare(lpd), print1(n, ", ")); ); } \\ Michel Marcus, Apr 19 2013

Crossrefs

Sequence in context: A195419 A110188 A069236 * A051370 A290614 A347640

Adjacent sequences: A187098 A187099 A187100 * A187102 A187103 A187104

Keyword

nonn

Author

Zak Seidov, Mar 04 2011

Status

approved