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A077798 Palindromic wing primes (a.k.a. near-repdigit palindromic primes) of the general form r*(10^d - 1)/9 + (m-r)*10^floor(d/2) where d is the number of digits (an odd number > 1), r is the repeated digit, and m (different from r) is the middle digit.

%I A077798 #30 Sep 08 2022 08:45:07
%S A077798 101,131,151,181,191,313,353,373,383,727,757,787,797,919,929,11311,
%T A077798 11411,33533,77377,77477,77977,1114111,1117111,3331333,3337333,
%U A077798 7772777,7774777,7778777,111181111,111191111,777767777,77777677777,99999199999,1111118111111
%N A077798 Palindromic wing primes (a.k.a. near-repdigit palindromic primes) of the general form r*(10^d - 1)/9 + (m-r)*10^floor(d/2) where d is the number of digits (an odd number > 1), r is the repeated digit, and m (different from r) is the middle digit.
%C A077798 Prime versus probable prime status and proofs are given in the author's table.
%D A077798 C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
%H A077798 Jon E. Schoenfield, <a href="/A077798/b077798.txt">Table of n, a(n) for n = 1..124</a>
%H A077798 Patrick De Geest, <a href="http://www.worldofnumbers.com/wing.htm">PWP Reference Table</a>
%H A077798 Ernest G. Hibbs, <a href="https://www.proquest.com/openview/4012f0286b785cd732c78eb0fc6fce80">Component Interactions of the Prime Numbers</a>, Ph. D. Thesis, Capitol Technology Univ. (2022), see p. 33.
%o A077798 (Magma) a:=[]; for d in [3..13 by 2] do for r in [1..9] do for m in [0..9] do if m ne r then t:=r*((10^d-1) div 9) + (m-r)*10^(d div 2); if IsPrime(t) then a[#a+1]:=t; end if; end if; end for; end for; end for; a; // _Jon E. Schoenfield_, Nov 04 2018
%Y A077798 Cf. A077775-A077797.
%K A077798 nonn,base
%O A077798 1,1
%A A077798 _Patrick De Geest_, Nov 16 2002
%E A077798 Offset corrected by _Arkadiusz Wesolowski_, Sep 13 2011
%E A077798 Name edited and one more term added by _Jon E. Schoenfield_, Nov 03 2018