A048438 Take the first n numbers written in base 6, concatenate them, then convert from base 6 to base 10.

1, 8, 51, 310, 1865, 67146, 2417263, 87021476, 3132773145, 112779833230, 4060073996291, 146162663866488, 5261855899193581, 189426812370968930, 6819365245354881495, 245497148832775733836, 8837897357979926418113

Offset

1,2

Comments

The first three primes in this sequence occur for n = 11 (a(11) = 4060073996291), n = 43 (a(43) =4.3194...*10^68), n = 173 (a(n) = 1.3014...*10^372) (email from Kurt Foster, Oct 24 2015). - N. J. A. Sloane, Oct 25 2015

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..200

Example

a(8) = (1)(2)(3)(4)(5)(10)(11)(12) = 12345101112_6 = 87021476.

Mathematica

If[STARTPOINT==1, n={}, n=Flatten[IntegerDigits[Range[STARTPOINT-1], 6]]]; Table[AppendTo[n, IntegerDigits[w, 6]]; n=Flatten[n]; FromDigits[n, 6], {w, STARTPOINT, ENDPOINT}] (* Dylan Hamilton, Aug 11 2010 *)
Table[FromDigits[Flatten[IntegerDigits[#, 6]&/@Range[n]], 6], {n, 20}] (* Harvey P. Dale, Sep 29 2012 *)

Prog

(Magma) [n eq 1 select 1 else Self(n-1)*6^(1+Ilog(6, n))+n: n in [1..20]]; // Vincenzo Librandi, Dec 30 2012

Crossrefs

Cf. A014829.

Concatenation of first n numbers in other bases: 2: A047778, 3: A048435, 4: A048436, 5: A048437, 6: this sequence, 7: A048439, 8: A048440, 9: A048441, 10: A007908, 11: A048442, 12: A048443, 13: A048444, 14: A048445, 15: A048446, 16: A048447.

Sequence in context: A037606 A055147 A014829 * A348312 A295602 A226199

Adjacent sequences: A048435 A048436 A048437 * A048439 A048440 A048441

Keyword

nonn,base,easy

Author

Patrick De Geest, May 15 1999

Status

approved