This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A212611 #18 Sep 14 2013 01:37:38 %S A212611 135,3375,25137,68607,22113,557375,451737,1278316,273,6739509,188325, %T A212611 8775,9020375,20365625,1083537,3416875,17875,1995,171387125,382536063, %U A212611 49166,366776,1487640245,417725 %N A212611 Primitive deficient numbers n having a companion m > n such that sigma(n)/n = sigma(m)/m (ordered by increasing (smallest possible) m). %C A212611 These numbers n = a(k) are listed in the order of increasing companions m = A212612(k). All these numbers appear to have only one companion. %F A212611 a(n) = A212610(2n-1). - _M. F. Hasler_, Feb 22 2013 %Y A212611 Cf. A211680 (pairs of deficient numbers). %Y A212611 Cf. A212610 (pairs of primitive deficient numbers). %K A212611 nonn,more %O A212611 1,1 %A A212611 _T. D. Noe_, May 23 2012 %E A212611 a(10)-a(18) from _Donovan Johnson_, May 24 2012 %E A212611 a(19)-a(24) from _Donovan Johnson_, Jun 06 2012