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 A109788 #19 Dec 31 2024 15:39:13 %S A109788 12,20,56,70,88,104,368,464,650,836,1888,1952,4030,5830,8925,11096, %T A109788 17816,32128,32445,45356,77744,91388,128768,130304,254012,388076, %U A109788 442365,521728,522752,1848964,2087936,2291936,8378368,8382464,13174976,29465852,35021696,45335936 %N A109788 Admirable numbers whose abundance is < 10. %C A109788 Apparently all the abundant numbers with even abundance < 10 are admirable (checked for the first 60 terms). Of the 4 known numbers whose abundance is 10 (A223609), only the first, 40, is admirable. - _Amiram Eldar_, Nov 07 2019 %H A109788 Amiram Eldar, <a href="/A109788/b109788.txt">Table of n, a(n) for n = 1..60</a> %t A109788 aQ[n_] := (ab = DivisorSigma[1, n] - 2 n) > 0 && EvenQ[ab] && ab < 10 && ab/2 < n && Divisible[n, ab/2]; Select[Range[10^4], aQ] (* _Amiram Eldar_, Nov 07 2019 *) %o A109788 (PARI) for(n=1,10^9,my(ap=sigma(n)-2*n); if(ap>0 && ap<10 && ap%2==0, my(d=ap/2); if(d!=n && n%d==0, print1(n, ", ")))) \\ Herman Jamke (hermanjamke(AT)fastmail.fm), Mar 30 2008 %Y A109788 Cf. A033880, A111592, A111667. %K A109788 nonn %O A109788 1,1 %A A109788 _Jason Earls_, Aug 14 2005 %E A109788 More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Mar 30 2008 %E A109788 a(36)-a(38) from _Amiram Eldar_, Nov 07 2019