OFFSET
1,3
COMMENTS
All terms have an odd number of digits. - Alonso del Arte, Jan 31 2020
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
FORMULA
MATHEMATICA
palQ[n_, b_:10] := (IntegerDigits[n, b] == Reverse[IntegerDigits[n, b]]); alternParQ[n_, b_:10] := (Union[BlockMap[Xor @@ # &, OddQ[IntegerDigits[n, b]], 2, 1]] == {True}); Join[Range[0, 9], Select[Range[1000], palQ[#] && alternParQ[#] &]] (* Alonso del Arte, Feb 02 2020 *)
Join[Range[0, 9], Select[Range[100000], PalindromeQ[#]&&Union[Total/@Partition[Boole[ EvenQ[ IntegerDigits[ #]]], 2, 1]] =={1}&]] (* Harvey P. Dale, Jul 04 2023 *)
PROG
(Haskell)
a030147 n = a030147_list !! (n-1)
a030147_list = filter ((== 1) . a228710) a002113_list
-- Reinhard Zumkeller, Aug 31 2013
(Scala) def isPal(n: Int) = (n.toString == n.toString.reverse)
def alternsPar(n: Int): Boolean = {
val dPars = Integer.toString(n).toList.map(_ % 2 == 0)
val scanPars = (dPars zip dPars.tail).map{ case (x, y) => x ^ y }
scanPars.toSet == Set(true)
}
(0 to 9) ++: (10 to 999).filter(isPal).filter(alternsPar) // Alonso del Arte, Feb 02 2020
CROSSREFS
KEYWORD
nonn,base
AUTHOR
STATUS
approved