cp's OEIS Frontend

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.

A294029 Values of bsigma(k) = bsigma(k+1), where bsigma is the sum of the bi-unitary divisors (A188999).

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%I A294029 #13 Jan 21 2020 10:23:22
%S A294029 24,40,60,720,960,1440,2160,2640,2400,3000,4320,4320,4320,5280,7400,
%T A294029 11520,11880,12960,14400,20160,30240,26640,34560,25200,34560,49920,
%U A294029 51840,60480,63360,60480,65280,62400,61560,115200,93600,114912,100800,120960,120960
%N A294029 Values of bsigma(k) = bsigma(k+1), where bsigma is the sum of the bi-unitary divisors (A188999).
%C A294029 The sum of bi-unitary divisors of numbers n such that n and n+1 have the same sum (A293183).
%C A294029 The bi-unitary version of A053215.
%H A294029 Amiram Eldar, <a href="/A294029/b294029.txt">Table of n, a(n) for n = 1..2148</a>
%F A294029 a(n) = A188999(A293183(n)).
%e A294029 24 is in the sequence since 24 = bsigma(14) = bsigma(15).
%t A294029 f[n_] := Select[Divisors[n], Function[d, CoprimeQ[d, n/d]]]; bsigma[m_] := DivisorSum[m, # &, Last@Intersection[f@#, f[m/#]] == 1 &]; a = {}; b1 = 0; For[k = 0, k < 10^6, k++; b2 = bsigma[k]; If[b1 == b2, a = AppendTo[a, b1]]; b1 = b2]; a (* after _Michael De Vlieger_ at A188999 *)
%Y A294029 Cf. A053215, A290303, A188999, A293183.
%K A294029 nonn
%O A294029 1,1
%A A294029 _Amiram Eldar_, Oct 22 2017