OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
EXAMPLE
a(n)=143 -> a(n)-reversed=341 gives pair (143,341) of which only the smaller value 143 is in this sequence.
MATHEMATICA
rev[n_]:=FromDigits[Reverse[IntegerDigits[n]]]; Select[Range[425], !PrimeQ[#]&&PrimeOmega[#]==PrimeOmega[x=rev[#]]&&#<x&] (* Jayanta Basu, May 31 2013 *)
PROG
(PARI) is(n)=my(r=fromdigits(Vecrev(digits(n)))); n<r && !isprime(n) && !isprime(r) && bigomega(n)==bigomega(r) \\ Charles R Greathouse IV, Oct 17 2018
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Aug 15 1999
EXTENSIONS
Name edited and offset corrected by Charles R Greathouse IV, Oct 17 2018
STATUS
approved