A161730 Palindromic numbers that are fixed points of the TITO operation (see A161594) and are not products of palindromic primes.

72927, 76167, 434434, 868868, 1226221, 4778774, 5703075, 8755578, 9386839, 13488431, 43877834, 123848321, 564414465, 777555777, 1072772701, 1946776491, 9935115399, 12467976421, 52854045825, 74663436647, 83361616338, 95829592859

Offset: 1

Author

Tanya Khovanova, Jun 17 2009

Keywords

• base
• nonn

Comments

The numbers in this sequence are palindromic numbers that are fixed points of the TITO operation and are not primes and are not in A046351.

Links

• M. F. Hasler, Table of n, a(n) for n = 1..35. [From _M. F. Hasler_, Jun 25 2009]
• T. Khovanova, Turning Numbers Inside Out [From _Tanya Khovanova_, Jul 07 2009]

Crossrefs

Cf. A161594, A161597, A161598, A161600.

Programs

Mathematica

reversepower[{n_, k_}] := FromDigits[Reverse[IntegerDigits[n]]]^k f[n_] := FromDigits[ Reverse[IntegerDigits[Times @@ Map[reversepower, FactorInteger[n]]]]] rev[n_] := FromDigits[Reverse[IntegerDigits[n]]] Select[Range[5000000], rev[ # ] == # && ! PrimeQ[ # ] && f[ # ] == # && Map[rev, Transpose[FactorInteger[ # ]][[1]]] != Transpose[FactorInteger[ # ]][[1]] &]

PARI

for( d=1,19, my(p=10^((d+1)\2),q=10^(d%2)); for( i=p\10,p-1, my(n = i\q*p+R(i),f); A161594(n)==n || next; apply(R,f=factor(n)[,1])==f && next; print1(n",") )) /* uses definitions given in A161594 */ \\ M. F. Hasler, Jun 25 2009

Extensions

Edited by N. J. A. Sloane, Jun 23 2009

Terms beyond a(6) from M. F. Hasler, Jun 25 2009