A070844 a(n) = smallest n-digit number with exactly n divisors, or 0 if no such number exists.

1, 11, 121, 1003, 14641, 100017, 1771561, 10000005, 100020001, 1000000016, 25937424601, 100000000004, 3138428376721, 10000000001344, 100000720001296, 1000000000000006, 45949729863572161, 100000000000000404

Offset

1,2

Links

Ray Chandler, Table of n, a(n) for n=1..41

Formula

If n is a prime < 29 then a(n) = 11^(n-1). - Chandler

If n is a prime >= 29 then a(n) = 0. - Vladeta Jovovic, Aug 20 2002

Mathematica

For[n=1, n<10, n++, k := 10^(n-1); While[Not[Length[Divisors[k]] == n], k++ ]; Print[k]] (Steinerberger)

Crossrefs

Cf. A070845.

Sequence in context: A293891 A218262 A006940 * A164327 A080445 A033867

Adjacent sequences: A070841 A070842 A070843 * A070845 A070846 A070847

Keyword

base,nonn

Author

Amarnath Murthy, May 12 2002

Extensions

a(6)-a(18) from Vladeta Jovovic, Aug 20 2002

a(6) confirmed by Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 08 2003

a(7)-a(10) confirmed by Stefan Steinerberger, Feb 06 2006

a(15) corrected, and a(11)-a(14), a(16)-a(18) confirmed by Ray Chandler, Feb 10 2009

Edited by N. J. A. Sloane, Feb 14 2009 at the suggestion of Ray Chandler.

Status

approved