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 A326304 #14 Jan 18 2020 20:40:56 %S A326304 1,2,3,2,3,6,7,2,5,6,7,6,7,14,9,2,3,10,11,6,21,14,15,6,5,14,9,14,15, %T A326304 18,19,2,21,6,21,10,11,22,21,6,7,42,43,14,15,30,31,6,37,10,9,14,15,18, %U A326304 21,14,33,30,31,18,19,38,35,2,21,42,43,6,45,42,43,10 %N A326304 Multiplicative with a(p^k) = a(p-1)^k + 1 for any k > 0 and any prime number p. %C A326304 The sequence is well defined as computing a(p^k) involves terms of the form a(q) with q < p. %C A326304 The fixed points are the divisors of 1806 = 2 * 3 * 7 * 43; they correspond to the first 16 terms of A191614. %H A326304 Rémy Sigrist, <a href="/A326304/b326304.txt">Table of n, a(n) for n = 1..10000</a> %e A326304 a(2) = a(1) + 1 = 1 + 1 = 2. %e A326304 a(3) = a(2) + 1 = 2 + 1 = 3. %e A326304 a(7) = a(6) + 1 = a(2)*a(3) + 1 = 2 * 3 + 1 = 7. %e A326304 a(43) = a(42) + 1 = a(2)*a(3)*a(7) + 1 = 2*3*7 + 1 = 43. %o A326304 (PARI) a(n) = my (f=factor(n)); prod (i=1, #f~, a(f[i,1]-1)^f[i,2]+1) %Y A326304 Cf. A191614, A309243. %K A326304 nonn,mult %O A326304 1,2 %A A326304 _Rémy Sigrist_, Oct 17 2019