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%I #16 Nov 22 2019 20:42:03
%S 1,2,3,4,10,17,688,1075,103681,7860997,10749957121,
%T 115561578124838522881,488296733939737583689,489501979450313254561,
%U 3628116960730713370000,8784132317383836036997,8784200214538920269317,50755107290462736080376601,94426187701102977738552612783157
%N Numbers m such that sigma(m) is a Lucas number (A000032), where sigma(m) is the sum of divisors of m (A000203).
%C Prime numbers of the form L(k)-1, where L(k) is the k-th Lucas number, are in this sequence. The terms 2, 3, 17, 103681, and 10749957121 are primes of this form (with k = 2, 3, 6, 24, 48). Also in the sequence is the prime L(96) - 1 = 115561578124838522881.
%H Daniel Suteu, <a href="/A329660/b329660.txt">Table of n, a(n) for n = 1..225</a>
%e 4 is in the sequence since sigma(4) = 7 is a Lucas number.
%t f = LucasL @ Range[1, 40]; Select[Range[10^6], MemberQ[f, DivisorSigma[1, #]] &] (* after _Giovanni Resta_ at A272412 *)
%Y Cf. A000032, A000203, A272412.
%K nonn
%O 1,2
%A _Amiram Eldar_, Nov 18 2019
%E a(12)-a(19) from _Giovanni Resta_, Nov 18 2019