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 A294926 #11 Mar 14 2024 03:47:58
%S A294926 0,1,1,2,1,3,1,3,2,3,1,4,1,3,3,4,1,4,1,5,3,3,1,5,2,3,3,5,1,6,1,5,3,3,
%T A294926 3,5,1,3,3,6,1,6,1,5,5,3,1,6,2,5,3,5,1,5,3,6,3,3,1,7,1,3,5,6,3,6,1,5,
%U A294926 3,7,1,6,1,3,5,5,3,6,1,7,4,3,1,7,3,3,3,7,1,8,3,5,3,3,3,7,1,5,5,7,1,6,1,7,7
%N A294926 Number of proper divisors of n that are deficient (A005100).
%H A294926 Antti Karttunen, <a href="/A294926/b294926.txt">Table of n, a(n) for n = 1..20000</a>
%F A294926 a(n) = Sum_{d|n, d<n} A294934(d).
%F A294926 a(n) = A080226(n) - A294934(n).
%F A294926 a(n) + A294927(n) = A032741(n).
%t A294926 a[n_] := DivisorSum[n, 1 &, # < n && DivisorSigma[1, #] < 2*# &]; Array[a, 100] (* _Amiram Eldar_, Mar 14 2024 *)
%o A294926 (PARI) A294926(n) = sumdiv(n, d, (d<n)*(sigma(d)<(2*d))); \\ _Antti Karttunen_, Nov 14 2017
%Y A294926 Cf. A032741, A080226, A294886, A294927, A294928, A294929, A294934.
%K A294926 nonn
%O A294926 1,4
%A A294926 _Antti Karttunen_, Nov 14 2017