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

Offset

1,2

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

Links

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

Example

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

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 *)

Prog

(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
(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

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.

Sequence in context: A037608 A055149 A014831 * A226202 A271557 A351750

Adjacent sequences: A048437 A048438 A048439 * A048441 A048442 A048443

Keyword

nonn,base,easy

Author

Patrick De Geest, May 15 1999

Status

approved