A085329 Non-palindromic solutions to sigma(Rev(n)) = sigma(n).

528, 825, 1561, 1651, 4064, 4604, 5346, 5795, 5975, 6435, 15092, 15732, 21252, 23751, 25212, 29051, 34536, 38115, 39325, 39516, 51183, 52393, 53295, 53768, 59235, 61593, 63543, 64328, 69368, 70577, 77507, 81558, 82346, 85518, 86396

Offset

1,1

Links

Donovan Johnson, Table of n, a(n) for n = 1..1000

Formula

Solutions to [A000203(x) = A000203(A004086(x))] && [A004086(n) <> n].

Example

sigma(528) = sigma(825) = 1488.

Mathematica

nd[x_, y_] := 10*x+y tn[x_] := Fold[nd, 0, x] red[x_] := Reverse[IntegerDigits[x]] Do[s=DivisorSigma[1, n]; s1=DivisorSigma[1, tn[red[n]]]; If[Equal[s, s1]&&!Equal[n, tn[red[n]]], Print[{n, s}]], {n, 1, 1000000}]
srnQ[n_]:=Module[{idn=IntegerDigits[n], ridn}, ridn=Reverse[idn]; idn!=ridn && DivisorSigma[1, n]==DivisorSigma[1, FromDigits[ridn]]]; Select[Range[ 100000], srnQ] (* Harvey P. Dale, Oct 25 2011 *)

Crossrefs

Cf. A000203, A004086, A062895.

Sequence in context: A250754 A158364 A232885 * A157475 A373285 A158365

Adjacent sequences: A085326 A085327 A085328 * A085330 A085331 A085332

Keyword

base,nonn

Author

Labos Elemer, Jul 04 2003

Status

approved