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A124141 Numbers k such that there is a number m < k satisfying A000203(k) = A000203(m) = m + k - gcd(m,k). 1

%I #19 Feb 08 2022 08:13:42

%S 38,92,153,284,332,459,494,885,956,1035,1358,1784,2295,2528,2678,5434,

%T 5607,6027,6255,7564,7928,8235,8648,9729,10325,10413,12008,14104,

%U 15813,16198,17794,22712,22936,23247,27082,27626,28917,30938,33082,34688,37790,37816

%N Numbers k such that there is a number m < k satisfying A000203(k) = A000203(m) = m + k - gcd(m,k).

%e 38 is in the sequence because A000203(24) = A000203(38) = 60 = 24 + 38 - gcd(24,38).

%o (PARI) isok(k) = {my(sk = sigma(k)); for (m=1, k, if ((sk == sigma(m)) && (sk == m + k - gcd(m,k)), return (1));); return (0);} \\ _Michel Marcus_, Oct 27 2019

%Y Cf. A000203, A124140.

%Y Subsequence of A069822.

%K nonn

%O 1,1

%A _Yasutoshi Kohmoto_, Dec 01 2006

%E Edited by _Stefan Steinerberger_, Aug 14 2007

%E More terms from _Jinyuan Wang_, Feb 07 2022

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Last modified March 29 00:26 EDT 2024. Contains 371264 sequences. (Running on oeis4.)