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%I #30 Sep 08 2022 08:44:57
%S 1,11,102,922,8303,74733,672604,6053444,490328973,39716646823,
%T 3217048392674,260580919806606,21107054504335099,1709671414851143033,
%U 138483384602942585688,11217154152838349440744,908589486379906304700281,73595748396772410680722779
%N Take the first n numbers written in base 9, concatenate them, then convert from base 9 to base 10.
%C The first two primes in this sequence occur for n = 2 (a(2) = 11) and n = 14 (a(14) = 1709671414851143033) (email from Kurt Foster, Oct 24 2015). - _N. J. A. Sloane_, Oct 25 2015
%H Vincenzo Librandi, <a href="/A048441/b048441.txt">Table of n, a(n) for n = 1..200</a>
%e a(9) = (1)(2)(3)(4)(5)(6)(7)(8)(10) = 1234567810_9 = 490328973.
%t If[STARTPOINT==1, n={}, n=Flatten[IntegerDigits[Range[STARTPOINT-1], 9]]]; Table[AppendTo[n, IntegerDigits[w, 9]]; n=Flatten[n]; FromDigits[n, 9], {w, STARTPOINT, ENDPOINT}] (* _Dylan Hamilton_, Aug 11 2010 *)
%t f[n_]:= FromDigits[Flatten@IntegerDigits[Range@n, 9], 9]; Array[f, 20] (* _Vincenzo Librandi_, Dec 30 2012 *)
%o (PARI) { cuo=0;
%o for(ixp=1, 18,
%o casi = ixp; cvst=0;
%o while(casi != 0,
%o cvd = casi%9; cvst=10*cvst + cvd + 1; casi = (casi - cvd) / 9 );
%o while(cvst !=0, ptch = cvst%10;
%o cuo=cuo*9+ptch-1; cvst = (cvst - ptch) / 10 ); print1(cuo, ", "))}
%o \\ _Douglas Latimer_, Apr 27 2012
%o (Magma) [n eq 1 select 1 else Self(n-1)*9^(1+Ilog(9, n))+n: n in [1..20]]; // _Vincenzo Librandi_, Dec 30 2012
%Y Cf. A014832, A055150.
%Y Concatenation of first n numbers in other bases: 2: A047778, 3: A048435, 4: A048436, 5: A048437, 6: A048438, 7: A048439, 8: A048440, 9: this sequence, 10: A007908, 11: A048442, 12: A048443, 13: A048444, 14: A048445, 15: A048446, 16: A048447.
%K nonn,base,easy
%O 1,2
%A _Patrick De Geest_, May 15 1999
%E More terms from _Douglas Latimer_, May 10 2012
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