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 A054574 #16 Feb 07 2022 22:04:19 %S A054574 23,11,17,23,47,41,53,59,71,89,167,113,269,131,167,191,179,227,239, %T A054574 263,251,239,251,269,293,431,311,359,383,383,383,479,479,419,449,881, %U A054574 2039,491,503,521,2039,659,2039,743,593,599,839,743,683,911,701,719,1103 %N A054574 Begin with n-th prime, add its prime divisors (itself), repeat until reach a new prime; sequence gives prime reached. %C A054574 Prime factors are counted with multiplicity. - _Sean A. Irvine_, Feb 07 2022 %H A054574 Amiram Eldar, <a href="/A054574/b054574.txt">Table of n, a(n) for n = 1..10000</a> %e A054574 a(5)=47 because starting with the 5th prime, 11: 11+11=22; 22+2+11=35; 35+5+7=47, a prime. %t A054574 f[n_] := n + Plus @@ Times @@@ FactorInteger@n; a[n_] := NestWhile[f, (p = Prime[n]), # == p || CompositeQ[#] &]; Array[a, 100] (* _Amiram Eldar_, Sep 07 2019 *) %Y A054574 Cf. A054575. %K A054574 easy,nonn %O A054574 1,1 %A A054574 _Enoch Haga_, Apr 11 2000 %E A054574 Corrected by _Jud McCranie_, Jan 04 2001