A071686 Smallest solution to gcd(x, Rev(x)) = 2^n.

2, 4, 8, 2192, 21920, 291008, 610688, 2112256, 2131456, 2937856, 25329664, 230465536, 694018048, 2344321024, 4688642048, 2112421888, 65012891648, 650128916480, 4494196736, 63769149440, 637691494400, 23842827272192, 276298064723968, 420127895977984, 4897795987210240

Offset

1,1

Links

Giovanni Resta, Table of n, a(n) for n = 1..32

Formula

a(n) = A069554(2^n).

Mathematica

a[n_] := Block[{k = 2^n}, While[GCD[k, FromDigits@ Reverse@ IntegerDigits@ k] != 2^n, k += 2^n]; k]; Array[a, 17] (* Giovanni Resta, Nov 14 2019 *)

Crossrefs

Cf. A004086, A055483, A069554, A072005, A072021, A072050.

Sequence in context: A067499 A135212 A012456 * A296742 A103097 A335750

Adjacent sequences: A071683 A071684 A071685 * A071687 A071688 A071689

Keyword

nonn,base

Author

Labos Elemer, Jun 03 2002

Extensions

a(22)-a(25) from Giovanni Resta, Oct 29 2019

Status

approved