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 A048442 #30 Sep 08 2022 08:44:57 %S A048442 1,13,146,1610,17715,194871,2143588,23579476,259374245,2853116705, %T A048442 345227121316,41772481679248,5054470283189021,611590904265871555, %U A048442 74002499416170458170,8954302429356625438586,1083470593952151678068923,131099941868210353046339701 %N A048442 Take the first n numbers written in base 11, concatenate them, then convert from base 11 to base 10. %H A048442 Vincenzo Librandi, <a href="/A048442/b048442.txt">Table of n, a(n) for n = 1..200</a> %e A048442 a(11) = (1)(2)(3)(4)(5)(6)(7)(8)(9)(A)(10) = 123456789A10_11 = 345227121316. %t A048442 If[STARTPOINT==1, n={}, n=Flatten[IntegerDigits[Range[STARTPOINT-1], 11]]]; Table[AppendTo[n, IntegerDigits[w, 11]]; n=Flatten[n]; FromDigits[n, 11], {w, STARTPOINT, ENDPOINT}] (* _Dylan Hamilton_, Aug 11 2010 *) %t A048442 f[n_]:= FromDigits[Flatten@IntegerDigits[Range@n, 11], 11]; Array[f, 20] (* _Vincenzo Librandi_, Dec 30 2012 *) %o A048442 (PARI) { cuo=0; %o A048442 for(ixp=1, 18, casi = ixp; cvst=0; %o A048442 while(casi != 0, %o A048442 cvd = casi%11; cvst=100*cvst + cvd + 1; casi = (casi - cvd) / 11 ); %o A048442 while(cvst !=0, ptch = cvst%100; %o A048442 cuo=cuo*11+ptch-1; cvst = (cvst - ptch) / 100 ); print1(cuo, ", "))} %o A048442 \\ _Douglas Latimer_, May 09 2012 %o A048442 (Magma) [n eq 1 select 1 else Self(n-1) * 11^(1+Ilog(11, n)) + n: n in [1..20]]; // _Vincenzo Librandi_, Dec 30 2012 %Y A048442 Cf. A014881. %Y A048442 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: this sequence, 12: A048443, 13: A048444, 14: A048445, 15: A048446, 16: A048447. %K A048442 nonn,base,easy %O A048442 1,2 %A A048442 _Patrick De Geest_, May 15 1999 %E A048442 1 more term from _Douglas Latimer_, May 10 2012