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 A056938 #32 Feb 16 2025 08:32:43
%S A056938 49,77,711,3379,31109,132393,344131,1731653,71143523,11115771019,
%T A056938 31135742029,717261644891,11193431873899,116134799345907,
%U A056938 3204751189066719,31068250396355573,62161149980213343,336906794442245927,734615161567701999,31318836286194043641
%N A056938 Concatenate all the prime divisors in previous term (with repetition), starting at 49.
%C A056938 This sequence provides a record of the search for the home prime for 49.
%C A056938 This sequence has now been followed for 117 steps without a prime being reached (after which of course it would simply repeat).
%H A056938 Patrick De Geest, <a href="/A056938/b056938.txt">Table of n, a(n) for n = 1..119</a>
%H A056938 P. De Geest, <a href="https://www.worldofnumbers.com/topic1.htm">Home Primes</a>
%H A056938 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HomePrime.html">Home Prime</a>
%t A056938 g[n_] := (x = n; d = {}; While[FactorInteger[x] != {}, f = FactorInteger[x, FactorComplete -> True][[1, 1]]; x = x/f; AppendTo[d, IntegerDigits[f]]]; FromDigits[Flatten[d]]); NestList[g, 49, 25]
%t A056938 (* Second program: *)
%t A056938 NestList[FromDigits@ Flatten@ Map[IntegerDigits, FactorInteger[#] /. {p_, e_} /; p >= 1 :> If[p == 1, 1, ConstantArray[p, e]]] &, 49, 16] (* _Michael De Vlieger_, Apr 27 2017 *)
%o A056938 (PARI) a=vector(35); a[1]=49; for(k=2,length(a), f=factor(a[k-1]); for(i=1,matsize(f)[1], l=10^ceil(log(f[i,1])/log(10)); for(j=1,f[i,2], a[k]=a[k]*l+f[i,1]))) \\ _M. F. Hasler_, Mar 09 2007
%Y A056938 Cf. A006919, A037273, A037274, A037271, A238579.
%K A056938 nonn,base
%O A056938 1,1
%A A056938 _Robert G. Wilson v_, Sep 05 2000
%E A056938 b-file updated by _Max Alekseyev_, Nov 28 2017