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 A087022 #19 Feb 16 2025 08:32:50 %S A087022 6,9,12,10,11,9,11,23,25,25,22,18,19,15,14,38,35,24,28,25,27,21,17,38, %T A087022 44,27,43,16,16,23,42,35,37,30,29,14,23,62,41,51,28,26,24,19,50,29,39, %U A087022 25,62,36,29 %N A087022 Total number of prime factors of n-th cyclic number. %C A087022 A004042(n) factorized with Dario Alpern's ECM. %C A087022 Extended using factors of 10^(A001913(n)-1)-1, see Kamada link. %H A087022 Dario A. Alpern, <a href="https://www.alpertron.com.ar/ECM.HTM">Factorization using the Elliptic Curve Method</a>. %H A087022 Makoto Kamada, <a href="https://stdkmd.net/nrr/repunit/">Factorizations of 11...11 (Repunit)</a> %H A087022 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CyclicNumber.html">Cyclic Number</a> %F A087022 a(n) = A001222(A004042(n+1)). %e A087022 A004042(2) = 142857 = 37*13*11*3^3, therefore a(1) = A087021(1)+2 = 6. %Y A087022 Cf. A001913, A087020-A087026. %K A087022 nonn,more,hard %O A087022 1,1 %A A087022 _Reinhard Zumkeller_, Jul 30 2003 %E A087022 a(3) corrected, a(12)-a(42) added by _Ray Chandler_, Nov 16 2011 %E A087022 a(43)-a(51) from _Max Alekseyev_, May 13 2022