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A161730
Palindromic numbers that are fixed points of the TITO operation (see A161594) and are not products of palindromic primes.
3
72927, 76167, 434434, 868868, 1226221, 4778774, 5703075, 8755578, 9386839, 13488431, 43877834, 123848321, 564414465, 777555777, 1072772701, 1946776491, 9935115399, 12467976421, 52854045825, 74663436647, 83361616338, 95829592859
OFFSET
1,1
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]
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]] &]
PROG
(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
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Tanya Khovanova, Jun 17 2009
EXTENSIONS
Edited by N. J. A. Sloane, Jun 23 2009
Terms beyond a(6) from M. F. Hasler, Jun 25 2009
STATUS
approved