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.
%I A137664 #8 Jan 10 2025 15:34:10
%S A137664 8,63,7775,2097151,743008370687,793714773254143,
%T A137664 2185911559738696531967,5242879999999999999999999,
%U A137664 55572324035428505185378394701823,6863037736488299999999999999999999999999999
%N A137664 a(n) = (p+1)^p - 1 where p = prime(n).
%C A137664 p^2 divides a(n) = (p+1)^p - 1, p = prime(n).
%C A137664 Quotients a(n)/prime(n)^2 are listed in A137665(n) = {2, 7, 311, 42799, 6140565047, 4696537119847, 7563707819165039903, ...}.
%C A137664 Least prime factors of A137665(n) = a(n)/prime(n)^2 are listed in A128456(n) = {2, 7, 311, 127, 23, 157, 7563707819165039903, ...}.
%C A137664 Largest prime factors A137665(n) = a(n)/prime(n)^2 are listed in A137666(n) = {2, 7, 311, 337, 266981089, 29914249171, 7563707819165039903, ...}.
%F A137664 a(n) = (prime(n) + 1)^prime(n) - 1.
%t A137664 Table[ (Prime[n] + 1)^Prime[n] - 1, {n,1,15} ]
%t A137664 (#+1)^#-1&/@Prime[Range[10]] (* _Harvey P. Dale_, Jan 10 2025 *)
%Y A137664 Cf. A128452, A128456, A128356, A128357, A137665, A137666.
%K A137664 nonn
%O A137664 1,1
%A A137664 _Alexander Adamchuk_, Feb 04 2008