A065734 Largest square <= sigma(n).

1, 1, 4, 4, 4, 9, 4, 9, 9, 16, 9, 25, 9, 16, 16, 25, 16, 36, 16, 36, 25, 36, 16, 49, 25, 36, 36, 49, 25, 64, 25, 49, 36, 49, 36, 81, 36, 49, 49, 81, 36, 81, 36, 81, 64, 64, 36, 121, 49, 81, 64, 81, 49, 100, 64, 100, 64, 81, 49, 144, 49, 81, 100, 121, 81, 144, 64, 121, 81, 144

Offset: 1

Author

Labos Elemer, Nov 15 2001

Keywords

• easy
• nonn

Links

• Harry J. Smith, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A048760, A000203, A065730-A065741.

Programs

Mathematica

Table[Floor[Sqrt[DivisorSigma[1,n]]]^2,{n,70}] (* Harvey P. Dale, Oct 05 2015 *)

Maxima

A000203(n) := divsum(n) ;
A048760(n) := (floor(sqrt(n)))^2 ;
A065734(n) := A048760(A000203(n)) ;
for n from 1 thru 10 do print(A065734(n)) ; /* R. J. Mathar, Feb 13 2012 */

PARI

a(n) = { sqrtint(sigma(n))^2 } \\ Harry J. Smith, Oct 28 2009

Formula

a(n) = A048760(A000203(n)).

Extensions

Previous Mathematica program replaced by Harvey P. Dale, Oct 05 2015