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Primes of the form highly abundant number + 1.
4

%I #12 Jun 07 2019 04:26:54

%S 2,3,5,7,11,13,17,19,31,37,43,61,73,97,109,181,211,241,337,421,541,

%T 601,631,661,1009,1201,1621,1801,2161,2341,2521,3121,3361,4201,4621,

%U 5881,6121,6301,7561,8821,9241,12241,12601,13441,15121,16381,18481,19801,20161,21841,23761,30241,35281

%N Primes of the form highly abundant number + 1.

%H Amiram Eldar, <a href="/A181561/b181561.txt">Table of n, a(n) for n = 1..1500</a>

%F {A002093(i) + 1} INTERSECTION A000040.

%F {1 + (sigma(n) > sigma(m) for all m < n + 1)} INTERSECTION A000040.

%e The 52nd highly abundant number is 1800, add one to get 1801 which is prime.

%t seq = {}; smax = 0; Do[s = DivisorSigma[1, n]; If[s > smax, smax = s; If[PrimeQ[n + 1], AppendTo[seq, n + 1]]], {n, 1, 10^4}]; seq (* _Amiram Eldar_, Jun 07 2019 *)

%Y Cf. A000040, A000203, A002093.

%K nonn,easy

%O 1,1

%A _Jonathan Vos Post_, Jan 29 2011