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 A289338 #6 Jan 05 2025 19:51:41
%S A289338 169,885,2193,8905,22713
%N A289338 Composite numbers (pseudoprimes) n, that are not Carmichael numbers, such that A000670(n) == 1 (mod n).
%C A289338 I. J. Good proved that A000670(n) == A000670(m) (mod p) for all primes p, and n == m (mod p-1). Therefore the congruence A000670(n) == 1 (mod n) holds for all primes and Carmichael numbers. This sequence consist of the other composite numbers for which the congruence holds.
%H A289338 I. J. Good, <a href="https://web.archive.org/web/2024*/https://www.fq.math.ca/Scanned/13-1/good.pdf">The number of orderings of n candidates when ties are permitted</a>, Fibonacci Quarterly, Vol. 13 (1975), pp. 11-18.
%t A289338 a[0] = 1; a[n_] := a[n] = Sum[Binomial[n, k]*a[n - k], {k, 1, n}]; carmichaelQ[n_]:=(Mod[n, CarmichaelLambda[n]] == 1); seqQ[n_] := !PrimeQ[n] && !carmichaelQ[n] && Divisible[a[n]-1,n]; Select[Range[2,500],seqQ]
%Y A289338 Cf. A000670, A002997, A289337.
%K A289338 nonn,more
%O A289338 1,1
%A A289338 _Amiram Eldar_, Jul 02 2017