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.

A348603 Larger member of a nonexponential amicable pair: numbers (k, m) such that nesigma(k) = m and nesigma(m) = k, where nesigma(k) is the sum of the nonexponential divisors of k (A160135).

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%I A348603 #6 Oct 25 2021 11:11:47
%S A348603 204,19332,168730,1099390,1292570,1598470,2062570,2429030,3077354,
%T A348603 3903012,4488910,6135962,5504110,5812130,7158710,8221598,9627915,
%U A348603 10893230,10043690,11049730,10273670,18087818,19150222,17578785,23030090,32174506,35997346,40117714,39944086
%N A348603 Larger member of a nonexponential amicable pair: numbers (k, m) such that nesigma(k) = m and nesigma(m) = k, where nesigma(k) is the sum of the nonexponential divisors of k (A160135).
%C A348603 The terms are ordered according to their smaller counterparts (A348602).
%e A348603 204 is a term since A160135(204) = 198 and A160135(198) = 204.
%t A348603 esigma[n_] := Times @@ (Sum[First[#]^d, {d, Divisors[Last[#]]}] &) /@ FactorInteger[n]; s[n_] := DivisorSigma[1, n] - esigma[n]; seq = {}; Do[m = s[n]; If[m > n && s[m] == n, AppendTo[seq, m]], {n, 1, 1.7*10^6}]; seq
%Y A348603 Cf. A160135, A348601, A348602.
%Y A348603 Similar sequences: A002046, A002953, A126166, A126170, A259039, A292981, A322542, A324709, A348344.
%K A348603 nonn
%O A348603 1,1
%A A348603 _Amiram Eldar_, Oct 25 2021