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 A077778 Palindromic wing primes (a.k.a. near-repdigit palindromes) of the form (10^a(n)-1) - 7*10^[ a(n)/2 ]. 1
 3, 17, 19, 705, 1061, 1395, 2631, 3837, 5749, 11753, 13537, 125877, 269479 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Prime versus probable prime status and proofs are given in the author's table. REFERENCES C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9. LINKS Patrick De Geest, World!Of Numbers, Palindromic Wing Primes (PWP's) Makoto Kamada, Prime numbers of the form 99...99299...99 FORMULA a(n) = 2*A115073(n)+1. EXAMPLE a(n)=17 -> (10^17-1)-7*10^8 = 99999999299999999. MATHEMATICA Do[ If[ PrimeQ[10^n - 7*10^Floor[n/2] - 1], Print[n]], {n, 3, 14600, 2}] (* Robert G. Wilson v, Dec 16 2005 *) CROSSREFS Cf. A004023, A077775-A077798, A107123-A107127, A107648, A107649, A115073, A183174-A183187. Sequence in context: A018750 A177208 A147845 * A273420 A022127 A273448 Adjacent sequences:  A077775 A077776 A077777 * A077779 A077780 A077781 KEYWORD more,nonn,base AUTHOR Patrick De Geest, Nov 16 2002 EXTENSIONS Added two more terms from PWP table, by Patrick De Geest, Nov 05 2014 STATUS approved

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