A335978 Numbers m of the form abs(k - reverse(k)) for at least one k.

0, 9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99, 180, 189, 198, 270, 279, 297, 360, 369, 396, 450, 459, 495, 540, 549, 594, 630, 639, 693, 720, 729, 792, 810, 819, 891, 900, 909, 990, 999, 1089, 1179, 1188, 1269, 1278, 1359, 1368, 1449, 1458, 1539, 1548, 1629, 1638, 1719, 1728, 1800, 1809, 1818, 1890, 1908, 1980, 1989, 1998, 2079

Offset

1,2

Comments

All terms are divisible by 9.

Let f(k) = k - reverse(k). Then f(reverse(k)) = -f(k), since f(reverse(k)) = reverse(k) - reverse(reverse(k)) = reverse(k) - k = - (k - reverse(k)) = -f(k).

Iteration of the function f(k) = k - reverse(k) leads to A072140, A072141, A072142, and A072143.

Links

Table of n, a(n) for n=1..64.

Michael P. Greaney, Remarkable Reversible Numbers, +plus magazine, (September 29, 2015).

Crossrefs

Cf. A056965, A067030, A072140, A072141, A072142, A072143.

Dividing by 9 gives A334145.

Sequence in context: A070279 A259729 A016096 * A070793 A052223 A085132

Adjacent sequences: A335975 A335976 A335977 * A335979 A335980 A335981

Keyword

nonn,base

Author

Michael Greaney, Jul 03 2020

Status

approved