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Strobogrammatic nonpalindromic numbers.
0

%I #6 Dec 15 2021 00:20:17

%S 69,96,609,619,689,906,916,986,1691,1961,6009,6119,6699,6889,6969,

%T 8698,8968,9006,9116,9696,9886,9966,16091,16191,16891,19061,19161,

%U 19861,60009,60109,60809,61019,61119,61819,66099,66199,66899,68089,68189,68889,69069,69169,69869,86098,86198,86898,89068,89168

%N Strobogrammatic nonpalindromic numbers.

%C Nonpalindromic numbers which are invariant under a 180-degree rotation.

%C Numbers that are the same upside down and containing digits 6, 9.

%C Intersection of A000787 and A029742.

%C Union of this sequence and A006072 gives A000787.

%t fQ[n_] := Block[{s = {0, 1, 6, 8, 9}, id = IntegerDigits[n]}, If[ Union[ Join[s, id]] == s && (id /. {6 -> 9, 9 -> 6}) == Reverse[id], True, False]]; Select[ Range[0, 89168], fQ[ # ] && ! PalindromeQ[ # ] &]

%Y Cf. A000787, A007597, A018848, A029742, A006072, A153806, A169731.

%K nonn,base

%O 1,1

%A _Ilya Gutkovskiy_, May 19 2017