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, 318164304887277351052086, 11453914975941984637875115

Offset: 1

Author

Patrick De Geest, May 15 1999

Keywords

• nonn
• base
• easy

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

Examples

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

Links

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

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.

Programs

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

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 *)