A051639 Concatenation of 3^k, k = 0,..,n.

1, 13, 139, 13927, 1392781, 1392781243, 1392781243729, 13927812437292187, 139278124372921876561, 13927812437292187656119683, 1392781243729218765611968359049, 1392781243729218765611968359049177147, 1392781243729218765611968359049177147531441

Offset: 0

Author

Felice Russo, Nov 15 1999

Keywords

• base
• nonn

Examples

			139 belongs to the sequence because it is the concatenation of 3^0, 3^1 and 3^2.
		

References

• A. Murthy, Smarandache Notions Journal, Vol. 11 N. 1-2-3 Spring 2000

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..63

Crossrefs

Cf. A000244. - R. J. Mathar, Oct 10 2010

Cf. A045507.

Programs

Maple

From R. J. Mathar, Oct 10 2010: (Start)
cat2 := proc(a,b) dgsb := max(1,ilog10(b)+1) ; a*10^dgsb+b ; end proc:
catL := proc(L) local a; a := op(1,L) ; for i from 2 to nops(L) do a := cat2(a,op(i,L)) ; end do; a; end proc:
A051639 := proc(n) catL([seq(3^k,k=0..n)]) ; end proc: seq(A051639(n),n=0..20) ; (End)
# second Maple program:
a:= proc(n) a(n):= `if`(n<0, 0, parse(cat(a(n-1), 3^n))) end:
seq(a(n), n=0..12);  # Alois P. Heinz, May 30 2021

Mathematica

With[{p3=3^Range[0,15]},Table[FromDigits[Flatten[IntegerDigits/@ Take[ p3,n]]],{n,15}]] (* Harvey P. Dale, Sep 13 2011 *)

Extensions

Terms n>=7 corrected by R. J. Mathar, Oct 10 2010