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%I #12 May 25 2024 17:52:30
%S 12,13,15,17,20,21,24,26,28,29,30,31,34,36,38,39,42,43,45,47,50,51,54,
%T 56,58,59,62,63,65,67,70,71,74,76,78,79,82,83,85,87,92,93,95,97,120,
%U 121,124,126,128,129,130,131,134,136,138,139
%N Numbers whose digits alternate between prime and nonprime.
%H Harvey P. Dale, <a href="/A085520/b085520.txt">Table of n, a(n) for n = 1..1000</a>
%e 151 is in the sequence as 1 is nonprime and 5 is prime.
%t dapnQ[n_]:=Module[{c=Boole[PrimeQ[IntegerDigits[n]]],len},len=Length[c];c==PadRight[{},len,{0,1}]||c==PadRight[{},len,{1,0}]]; Select[ Range[ 10,200],dapnQ] (* _Harvey P. Dale_, Jul 21 2019 *)
%K nonn,base
%O 1,1
%A Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jul 02 2003
%E Corrected (120 inserted) by _Harvey P. Dale_, Jul 21 2019
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