A260988 - OEIS

%I #10 Jan 17 2020 10:44:41

%S 8505,25500,30360,37740,40740,123795,141480,185460,442365,485400,

%T 834435,953568,1055460,1097820,1108320,1397220,1953960,2088480,

%U 2208840,2571744,3050784,3342816,3544695,3810456,4314156,4725660,4867236,5638776,6318180,6596340,8428320,8630832,9347280,9576336,9908460,10271580,10992360,11789925

%N Numbers n such that sigma(n) = m*sigma(n+2) with some m > 1.

%C Sequence A227304 is the union of A055574 and { a(n)+1 }.

%C Many but not all terms are multiples of 5.

%o (PARI) for(n=1,2e9,sigma(n)%sigma(n+2)||sigma(n)==sigma(n+2)||print1(n","))

%Y Cf. A000203, A055574, A067130, A058073.

%K nonn

%O 1,1

%A _M. F. Hasler_, Aug 06 2015