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 A086806 #15 Jun 29 2019 02:25:16
%S A086806 341,13747,19951,35333,60787,137149,150851,387731,458989,617093,
%T A086806 769757,1104349,1251949,1277179,1397419,1463749,1507963,1826203,
%U A086806 2134277,2205967,2617451,2976487,3345773,4361389,6474691,6955541,8095447
%N A086806 Sarrus numbers k such that k-1 and k+1 have the same number of prime divisors (counted with multiplicity).
%H A086806 Amiram Eldar, <a href="/A086806/b086806.txt">Table of n, a(n) for n = 1..10000</a>
%e A086806 341 is a pseudoprime to base 2 while 340 = 2^2*5*17 and 342 = 2*3^2*19 each have four primes dividing them.
%t A086806 PrimeFactorExponentsAdded[n_] := Plus @@ Flatten[ Table[ # [[2]], {1}] & /@ FactorInteger[n]]; Select[ Range[9224390], !PrimeQ[ # ] && PowerMod[2, # - 1, # ] == 1 && PrimeFactorExponentsAdded[ # - 1] == PrimeFactorExponentsAdded[ # + 1] & ]
%Y A086806 Intersection of A001567 and A280382.
%Y A086806 Cf. A001222.
%K A086806 nonn
%O A086806 1,1
%A A086806 _Jason Earls_, Aug 05 2003
%E A086806 More terms from _Robert G. Wilson v_, Aug 13 2003