A332194
a(n) = 10^(2n+1) - 1 - 5*10^n.
Original entry on oeis.org
4, 949, 99499, 9994999, 999949999, 99999499999, 9999994999999, 999999949999999, 99999999499999999, 9999999994999999999, 999999999949999999999, 99999999999499999999999, 9999999999994999999999999, 999999999999949999999999999, 99999999999999499999999999999, 9999999999999994999999999999999
Offset: 0
Cf.
A138148 (cyclops numbers with binary digits only),
A002113 (palindromes).
Cf.
A332114 ..
A332184 (variants with different repeated digit 1, ..., 8).
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A332194 := n -> 10^(n*2+1)-1-5*10^n;
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Array[ 10^(2 # + 1) -1 -5*10^# &, 15, 0]
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apply( {A332194(n)=10^(n*2+1)-1-5*10^n}, [0..15])
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def A332194(n): return 10**(n*2+1)-1-5*10^n
A077782
Numbers k such that (10^k - 1) - 5*10^floor(m/2) is a palindromic wing prime (a.k.a. near-repdigit palindromic prime).
Original entry on oeis.org
29, 45, 73, 209, 2273, 35729, 50897
Offset: 1
29 is a term because (10^29 - 1) - 5*10^14 = 99999999999999499999999999999.
- C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
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Do[ If[ PrimeQ[10^n - 5*10^Floor[n/2] - 1], Print[n]], {n, 3, 50900, 2}] (* Robert G. Wilson v, Dec 16 2005 *)
Showing 1-2 of 2 results.
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