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 A239502 #31 Feb 16 2025 08:33:21 %S A239502 4,10,74,212,1856,5618,53114,1630932,5161442,167427844,1729192432, %T A239502 5577731626,58401766802,2005139696964,69737304018266,228184540445268, %U A239502 8043367476888770,86866463049858250,285815985033409648,10225367934387562098,111384745483589787826 %N A239502 (Round(q^prime(n)) - 1)/prime(n), where q is the tribonacci constant (A058265). %C A239502 For n>=3, round(q^prime(n)) == 1 (mod 2*prime(n)). Proof in Shevelev link. In particular, all terms are even. %H A239502 S. Litsyn and V. Shevelev, <a href="http://dx.doi.org/10.1142/S1793042105000339">Irrational Factors Satisfying the Little Fermat Theorem</a>, International Journal of Number Theory, vol.1, no.4 (2005), 499-512. %H A239502 V. Shevelev, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2014-March/012750.html">A property of n-bonacci constant</a>, Seqfan (Mar 23 2014) %H A239502 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TribonacciConstant.html">Tribonacci Constant</a> %e A239502 For n=3, q^5 = 21.049..., so a(3) = (21 - 1)/5 = 4. %Y A239502 Cf. A007619, A007663, A238693, A238697, A238698, A238700, A058265. %K A239502 nonn %O A239502 3,1 %A A239502 _Vladimir Shevelev_ and _Peter J. C. Moses_, Mar 20 2014