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%I #12 Jun 24 2022 08:30:15
%S 1,4,6,8,9,101,111,141,161,181,191,202,212,242,262,282,292,303,313,
%T 343,363,383,393,404,414,444,464,484,494,505,515,545,565,585,595,606,
%U 616,646,666,686,696,707,717,747,767,787,797,808,818,848,868,888,898,909
%N Palindromic numbers with nonprime middle digit.
%p ts_num_midpal := proc(n) local ad,adr,midigit; ad := convert(n,base,10): adr := ListTools[Reverse](ad): if nops(ad) mod 2 = 0 then return 1; fi; midigit := op( (nops(ad)+1)/2,ad ): if (isprime( midigit )='false' and adr=ad) then return 0; else return 1; fi end: ts_n_pal := proc(n) if ts_num_midpal(n) = 0 then return (i) fi end: anpal := [seq(ts_n_pal(i), i=1..50000)]: anpal;
%o (Python)
%o from itertools import chain, count, islice
%o def A076612_gen(): # generator of terms
%o return chain((1,4,6,8,9),chain.from_iterable((int((s:=str(d))+e+s[::-1]) for d in range(10**l,10**(l+1)) for e in '014689') for l in count(0)))
%o A076612_list = list(islice(A076612_gen(),20)) # _Chai Wah Wu_, Jun 23 2022
%Y Cf. A002113.
%K easy,nonn,base
%O 1,2
%A _Jani Melik_, Oct 21 2002
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