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 A048444 #29 Jun 13 2025 10:49:47
%S A048444 1,15,198,2578,33519,435753,5664796,73642356,957350637,12445558291,
%T A048444 161792257794,2103299351334,355457590375459,60072332773452585,
%U A048444 10152224238713486880,1715725896342579282736,289957676481895898782401,49002847325440406894225787
%N A048444 Take the first n numbers written in base 13, concatenate them, then convert from base 13 to base 10.
%C A048444 No primes in the first 31000 terms. - _Giovanni Resta_, Jun 08 2018
%H A048444 Vincenzo Librandi, <a href="/A048444/b048444.txt">Table of n, a(n) for n = 1..200</a>
%e A048444 a(12) = (1)(2)(3)(4)(5)(6)(7)(8)(9)(A)(B)(C) = 123456789ABC_13 = 2103299351334.
%t A048444 If[STARTPOINT==1, n={}, n=Flatten[IntegerDigits[Range[STARTPOINT-1], 13]]]; Table[AppendTo[n, IntegerDigits[w, 13]]; n=Flatten[n]; FromDigits[n, 13], {w, STARTPOINT, ENDPOINT}] (* _Dylan Hamilton_, Aug 11 2010 *)
%t A048444 f[n_]:= FromDigits[Flatten@IntegerDigits[Range@n, 13], 13]; Array[f, 20] (* _Vincenzo Librandi_, Dec 30 2012 *)
%o A048444 (Magma) [n eq 1 select 1 else Self(n-1)*13^(1+Ilog(13, n))+n: n in [1..20]]; // _Vincenzo Librandi_, Dec 30 2012
%Y A048444 Cf. A014896.
%Y A048444 Concatenation of first n numbers in other bases: 2: A047778, 3: A048435, 4: A048436, 5: A048437, 6: A048438, 7: A048439, 8: A048440, 9: A048441, 10: A007908, 11: A048442, 12: A048443, 13: this sequence, 14: A048445, 15: A048446, 16: A048447.
%K A048444 nonn,base,easy
%O A048444 1,2
%A A048444 _Patrick De Geest_, May 15 1999