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 A125493 #12 Jan 06 2019 04:05:27 %S A125493 4,8,9,10,14,15,16,21,22,25,26,27,32,33,34,35,38,39,44,45,46,49,50,51, %T A125493 52,55,57,58,62,63,64,65,68,69,74,75,76,77,81,82,85,86,87,91,92,93,94, %U A125493 95,98,99,105,106,110,111,115,116,117,118,119,121,122,123,124,125,128 %N A125493 Composite deficient numbers. %H A125493 Harvey P. Dale, <a href="/A125493/b125493.txt">Table of n, a(n) for n = 1..1000</a> %e A125493 22 is in the sequence because it is composite and its sum of divisors 1 + 2 + 11 + 22 = 36 is less than 2*22. %e A125493 The integer 15 is in the sequence because it is composite and the sum of its proper divisors is 1 + 3 + 5 < 15. The integer 18 is not in the sequence because, although composite, the sum of its proper divisors is 1 + 2 + 3 + 6 + 9 > 18. %p A125493 with(numtheory): a:=proc(n) if sigma(n)<2*n and bigomega(n)>1 then n else fi end: seq(a(n),n=1..160); # _Emeric Deutsch_, Jan 01 2007 %t A125493 Select[Range[200],CompositeQ[#]&&DivisorSigma[1,#]<2#&] (* _Harvey P. Dale_, Mar 27 2016 *) %Y A125493 Cf. A002808 (composite numbers), A005100 (deficient numbers). %K A125493 nonn %O A125493 1,1 %A A125493 _Tanya Khovanova_, Dec 27 2006 %E A125493 More terms from _Emeric Deutsch_, Jan 01 2007