A182750 a(n) = the largest multiple of n with n digits and exactly n divisors; a(n) = 0 if no such number exists.

1, 0, 0, 0, 0, 0, 0, 99999992, 998117649, 0, 25937424601, 999999999924, 0, 0, 0, 9999999999999872, 0, 999999999999999252, 0, 99999999999999999440, 0, 0, 0, 999999999999999999999456, 9999450940359923567250625, 0, 999999999997420003910299449, 9999999999999999999999972416, 0, 0, 0

Offset: 1

Author

Jaroslav Krizek, Nov 27 2010

Keywords

• nonn
• base

Comments

Conjecture: a(n) > 0 for all nonsquarefree n except for n = 4. - Jon E. Schoenfield, Jun 01 2024

Crossrefs

Cf. A000005, A073904, A182749.

Formula

A000005(a(n)) = n if a(n) > 0.

a(n) >= A182749(n).

Extensions

More terms from Harvey P. Dale, Mar 02 2018

a(24)-a(25) and a(27) from Michael S. Branicky, May 26 2024

a(26), a(28) added, and a(16), a(18), a(20) corrected by Jon E. Schoenfield, May 26 2024

a(29)-a(31) from David A. Corneth, May 27 2024