A048440 Take the first n numbers written in base 8, concatenate them, then convert from base 8 to base 10.

1, 10, 83, 668, 5349, 42798, 342391, 21913032, 1402434057, 89755779658, 5744369898123, 367639673479884, 23528939102712589, 1505852102573605710, 96374534564710765455, 6167970212141488989136, 394750093577055295304721, 25264005988931538899502162

Offset: 1

Author

Patrick De Geest, May 15 1999

Keywords

• nonn
• base
• easy

Comments

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

Examples

			a(9): (1)(2)(3)(4)(5)(6)(7)(10)(11) = 12345671011_8 = 1402434057.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..390

Crossrefs

Cf. A014831.

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.

Programs

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

Mathematica

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 *)
Table[FromDigits[Flatten[IntegerDigits[#,8]&/@Range[n]],8],{n,20}] (* Harvey P. Dale, Dec 07 2012 *)

Python

from functools import reduce
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