A138299 For number bases b (2 <= b <= 10) consider numbers that can be written as repdigits with at least two digits: the sequence gives products of such numbers also having this property (the number bases are not necessarily distinct).

9, 12, 15, 16, 18, 20, 21, 24, 27, 28, 30, 32, 33, 35, 36, 40, 42, 44, 45, 48, 50, 54, 55, 60, 63, 66, 70, 77, 80, 88, 91, 93, 99, 121, 124, 129, 156, 171, 172, 182, 215, 219, 228, 242, 255, 273, 285, 292, 312, 333, 341, 342, 364, 365, 400, 438, 444, 455, 468, 511, 546

Offset

1,1

Links

R. Zumkeller, Table of n, a(n) for n = 1..250

R. Zumkeller, RepDigit Products

Eric Weisstein's World of Mathematics, Repeating Decimal

Eric Weisstein's World of Mathematics, Base

Example

a(20) = 48 = 3*16:     66_7  =  11_2 *  22_7;
a(21) = 50 = 5*10:     55_9  =  11_4 *  22_4;
a(22) = 54 = 3*18:     66_8  =  11_2 *  33_5;
a(23) = 55 = 5*11:     55_10 =  11_4 *  11_10;
a(24) = 60 = 3*20:     66_9  =  11_2 *  22_9;
a(25) = 63 = 3*21: 111111_2  =  11_2 * 111_4;
a(26) = 66 = 3*22:     66_10 =  11_2 *  22_10;
a(27) = 70 = 5*14:     77_9  =  11_4 *  22_6;
a(28) = 77 = 7*11:     77_10 = 111_2 *  11_10;
a(29) = 80 = 4*20:   2222_3  =  11_3 *  22_9.

Crossrefs

Sequence in context: A336756 A114306 A009188 * A050435 A176656 A377873

Adjacent sequences: A138296 A138297 A138298 * A138300 A138301 A138302

Keyword

nonn,base

Author

Reinhard Zumkeller, Mar 14 2008

Status

approved