A066598 Numbers which can be expressed as the product of a number and its reversal in four different ways.

1015560, 1446480, 1854720, 10155600, 14464800, 18547200, 51665040, 59552640, 67944240, 78127560, 82623060, 88560360, 95236960, 99497160, 101556000, 105094080, 108656860, 110937960, 117681480, 118072080, 124942090, 135647680

Offset: 1

Author

Robert G. Wilson v, Jan 08 2002

Keywords

• nonn
• base

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..10000
• Shyam Sunder Gupta, Equal Product of Reversible Numbers (EPRN), Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 12, 353-365.

Crossrefs

Cf. A066531.

Programs

Mathematica

f[n_] := (m = ToExpression[StringReverse[ToString[n]]]; If[n > m, n*m, 0]); a = Sort[ Table[ f[n], {n, 0, 10^6}]]; While[ a[[1]] == 0, a = Drop[a, 1]]; a[[ Select[ Range[ Length[a]] - 3, a[[ # ]] == a[[ # + 3 ]] & ]]]