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%I #16 Apr 19 2019 11:25:32
%S 2,4,6,16,18,42,100,156,162,256,486,1458,2028,4422,6162,14406,19182,
%T 22650,23548,26406,37056,39366,62500,65536,77658,113232,121452,143262,
%U 208392,292140,342732,375156,412806,527802,564898,590592,697048,843642
%N Numbers representable in exactly two ways as (p-1)*p^e (where p is a prime and e >= 0) in ascending order.
%C Numbers that are one less than a prime number and of the form (p-1)*p^e for some prime p and e > 0. - _Jianing Song_, Apr 13 2019
%H Jianing Song, <a href="/A114874/b114874.txt">Table of n, a(n) for n = 1..162</a> (all terms below 10^8)
%e 6 is a member because 6 = (3-1)*3^1 = (7-1)*7^0 and 3 and 7 are primes.
%t s = Split@Sort@Flatten@Table[(Prime[n] - 1)Prime[n]^k, {n, 68000}, {k, 0, 16}]; Union@Flatten@Select[s, Length@# == 2 &] (* _Robert G. Wilson v_, Jan 05 2006 *)
%o (PARI) isA114874(n) = if(n>1, my(v=factor(n), d=#v[, 1], p=v[d,1], e=v[d,2]); (isprime(n+1) && n==(p-1)*p^e), 0) \\ _Jianing Song_, Apr 13 2019
%Y Cf. A114871, A114873.
%K nonn
%O 1,1
%A _Franz Vrabec_, Jan 03 2006
%E a(13)-a(38) from _Robert G. Wilson v_, Jan 05 2006
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