Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 4500 articles have referenced us, often saying "we would not have discovered this result without the OEIS".
1,2
Table of n, a(n) for n=1..65.
{n: A007407(n) in A000290} . - R. J. Mathar, Oct 03 2014
Select[Range[300], IntegerQ[Sqrt[Denominator[Sum[1/k^2, {k, #}]]]]&] (* Harvey P. Dale, Mar 28 2012 *)
Cf. A007407, A073527.
Sequence in context: A242415 A242420 A242419 * A032992 A190298 A069118
Adjacent sequences: A073523 A073524 A073525 * A073527 A073528 A073529
nonn,easy
N. J. A. Sloane, Aug 30 2002
More terms from Matthew Conroy, Sep 09 2002
approved