A020337 Numbers whose base-9 representation is the juxtaposition of two identical strings.

10, 20, 30, 40, 50, 60, 70, 80, 738, 820, 902, 984, 1066, 1148, 1230, 1312, 1394, 1476, 1558, 1640, 1722, 1804, 1886, 1968, 2050, 2132, 2214, 2296, 2378, 2460, 2542, 2624, 2706, 2788, 2870, 2952, 3034, 3116, 3198, 3280, 3362, 3444, 3526, 3608, 3690, 3772

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = n*9^floor(log_9(n)+1) + n. - Ilya Gutkovskiy, Jan 26 2018

Example

902_10 = 1212_9. - Jon E. Schoenfield, Feb 12 2021

Mathematica

a[n_] := n + n*9^Floor[Log[9, n] + 1]; Array[a, 50] (* Amiram Eldar, Apr 06 2021 *)

Crossrefs

Cf. A020330, A020331, A020332, A020333, A020334, A020335, A020336, A020338.

Sequence in context: A371462 A033022 A031497 * A044835 A033007 A127993

Adjacent sequences: A020334 A020335 A020336 * A020338 A020339 A020340

Keyword

nonn,base

Author

David W. Wilson, Melia Aldridge (ma38(AT)spruce.evansville.edu)

Status

approved