|
%I #39 Feb 26 2023 14:40:11
%S 1,10,83,668,5349,42798,342391,21913032,1402434057,89755779658,
%T 5744369898123,367639673479884,23528939102712589,1505852102573605710,
%U 96374534564710765455,6167970212141488989136,394750093577055295304721
%N Take the first n numbers written in base 8, concatenate them, then convert from base 8 to base 10.
%C 83 is the only prime in this sequence among the first 3000 terms (email from Kurt Foster, Oct 24 2015). - _N. J. A. Sloane_, Oct 25 2015
%H Harvey P. Dale, <a href="/A048440/b048440.txt">Table of n, a(n) for n = 1..390</a>
%e a(9): (1)(2)(3)(4)(5)(6)(7)(10)(11) = 12345671011_8 = 1402434057.
%t If[STARTPOINT==1, n={}, n=Flatten[IntegerDigits[Range[STARTPOINT-1], 8]]]; Table[AppendTo[n, IntegerDigits[w, 8]]; n=Flatten[n]; FromDigits[n, 8], {w, STARTPOINT, ENDPOINT}] (* _Dylan Hamilton_, Aug 11 2010 *)
%t Table[FromDigits[Flatten[IntegerDigits[#,8]&/@Range[n]],8],{n,20}] (* _Harvey P. Dale_, Dec 07 2012 *)
%o (Magma) [n eq 1 select 1 else Self(n-1)*8^(1+Ilog(8, n))+n: n in [1..20]]; // _Vincenzo Librandi_, Dec 30 2012
%o (Python)
%o from functools import reduce
%o def A048440(n): return reduce(lambda i,j:(i<<3*(1+(j.bit_length()-1)//3))+j,range(n+1)) # _Chai Wah Wu_, Feb 26 2023
%Y Cf. A014831.
%Y Concatenation of first n numbers in other bases: 2: A047778, 3: A048435, 4: A048436, 5: A048437, 6: A048438, 7: A048439, 8: this sequence, 9: A048441, 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
|
