A175915 - OEIS

%I #9 May 13 2013 01:49:15

%S 2205,312896925,1874196225,3356107425,4181881725,4987853325,

%T 6946213725,8860349025,13250605725,17989980525,25443641025,

%U 32177090925,38286871425,55531730925,75756402225,113679103725,152738872209,170812073025,179835853725,186091427025

%N Odd terms of A109510.

%C a(1)=2205=A109510(29), a(2)-a(8) from Max Alekseyev.

%C sqrt(sigma(a(n))-2*a(n)): 6, 3432, 8250, 11022, 19376.

%o (PARI) is(n)=n%2&&issquare(sigma(n)-2*n) \\ _Charles R Greathouse IV_, Dec 06 2011

%Y Cf. A109510 sigma(n)-2n is a square.

%K nonn

%O 1,1

%A _Zak Seidov_, Oct 15 2010

%E a(6)-a(18) from _Donovan Johnson_, Oct 17 2010

%E a(19)-a(20) from _Donovan Johnson_, Dec 06 2011