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 A101260 #26 Sep 08 2022 08:45:16 %S A101260 84,140,224,308,364,476,532,644,812,868,1036,1148,1204,1316,1372,1484, %T A101260 1652,1708,1876,1988,2044,2212,2324,2492,2716,2828,2884,2996,3052, %U A101260 3164,3556,3668,3836,3892,4172,4228,4396,4544,4564,4676,4844,5012,5068,5348 %N A101260 Numbers n whose abundance is 56. %C A101260 If n is of the form p*28, where p is a prime distinct from 2 or 7 then n is in this sequence, note that 28 is a perfect number. The terms in the sequence but not divisible by 28 are 4544, 9272, 14552, 25472, 74992, 495104... - _Enrique Pérez Herrero_, Apr 15 2012 %C A101260 If p=2^k-57 is prime (cf. A165778), then 2^(k-1)*p is in the sequence: For the first such k=6,7,8,10,16,19,22,28,..., this yields 224, 4544, 25472, 495104, 2145615872, 137424011264, 8795973484544, 36028789368553472, ... - _M. F. Hasler_, Apr 15 2012 %H A101260 Enrique Pérez Herrero, <a href="/A101260/b101260.txt">Table of n, a(n) for n = 1..3000</a> %H A101260 F. Firoozbakht and M. F. Hasler, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL13/Hasler/hasler2.html">Variations on Euclid's formula for Perfect Numbers</a>, JIS 13 (2010) #10.3.1. %e A101260 84 is a term of the sequence because 2*2*3*7 = 84 and 84 - 42 - 28 - 21 - 14 - 12 - 7 - 6 - 4 - 3 - 2 = g(84) = -55. %t A101260 Select[ Range[5500], DivisorSigma[1, # ] == 2# + 56 &] (* _Robert G. Wilson v_, Dec 22 2004 *) %o A101260 (Magma) [n: n in [1..10^4] |DivisorSigma(1,n) eq 2*n+56]; // _Vincenzo Librandi_, Jul 30 2015 %Y A101260 Cf. A005101, A033880. %Y A101260 Cf. A141545, A141546. %K A101260 nonn,easy %O A101260 1,1 %A A101260 Vassil K. Tintschev (tinchev(AT)sunhe.jinr.ru), Dec 17 2004