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 A125640 #11 Mar 11 2024 04:18:27
%S A125640 24,30,42,54,66,78,102,114,138,140,174,176,186,222,224,246,258,282,
%T A125640 308,318,340,354,364,366,380,402,426,438,440,474,476,498,520,532,534,
%U A125640 580,582,606,618,642,644,654,678,762,786,812,822,834,868,894
%N A125640 Primitive doubly abundant numbers - doubly abundant numbers that are not the multiple of another doubly abundant number.
%C A125640 Are there infinitely many primitive doubly abundant numbers?
%H A125640 Reinhard Zumkeller, <a href="/A125640/b125640.txt">Table of n, a(n) for n = 1..10000</a>
%e A125640 42 is a primitive doubly abundant number because it is abundant (s(42) = 54), the sum of its proper divisors is abundant (s(54) = 66) and no divisor of 42 is doubly abundant.
%t A125640 s[n_] := DivisorSigma[1, n] - n; q[n_] := Module[{s1 = s[n]}, s1 > n && s[s1] > s1]; primQ[n_] := q[n] && !AnyTrue[Most[Divisors[n]], q]; Select[Range[900], primQ] (* _Amiram Eldar_, Mar 11 2024 *)
%o A125640 (Haskell)
%o A125640 import Data.List (intersect)
%o A125640 a125640 n = a125640_list !! (n-1)
%o A125640 a125640_list = f a125639_list [] where
%o A125640 f (x:xs) ys = if null (a027751_row' x `intersect` ys)
%o A125640 then x : f xs (x : ys) else f xs ys
%o A125640 -- _Reinhard Zumkeller_, Oct 31 2015
%Y A125640 Cf. A005101, A125639.
%Y A125640 Cf. A027751.
%K A125640 nonn
%O A125640 1,1
%A A125640 Gabriel Cunningham (gabriel.cunningham(AT)gmail.com), Nov 28 2006
%E A125640 Data corrected by _Reinhard Zumkeller_, Oct 31 2015