A068121 Smallest n-th power beginning with the concatenation of first n natural numbers.

1, 121, 12326391, 1234134359056, 1234543668832, 1234566439851412003312246012968681, 123456718029050407240974433459138845096817901

Offset

1,2

Comments

B-file stops at a(25) because a(26) has 1107 digits. - Giovanni Resta, Jul 12 2016

Links

Ray Chandler, Table of n, a(n) for n = 1..25

Example

12326391 = 231^3 is the smallest cube beginning with 123.

Mathematica

a[n_] := Block[{t = Flatten@ Table[ IntegerDigits@i, {i, n}], m, v, h = 0}, m = Length@t; z = FromDigits@t; While[ Take[ IntegerDigits[(v = Ceiling[(z 10^h) ^ (1/n)])^n], m] != t, h++]; v^n]; Array[a, 25] (* Giovanni Resta, Jul 12 2016 *)

Crossrefs

Cf. A068122.

Sequence in context: A053885 A068490 A077735 * A013859 A303897 A060032

Adjacent sequences: A068118 A068119 A068120 * A068122 A068123 A068124

Keyword

base,nonn

Author

Amarnath Murthy, Feb 21 2002

Extensions

More terms from Robert Gerbicz, Sep 05 2002

Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, Jun 15 2007

Status

approved