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 A108903 Numbers such that the outer 2 digits are 9 and the inner digits are 5. 0
 959, 9559, 95559, 955559, 9555559, 95555559, 955555559, 9555555559, 95555555559, 955555555559, 9555555555559, 95555555555559, 955555555555559, 9555555555555559, 95555555555555559, 955555555555555559 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS These numbers are all composite. They are divisible among other numbers by 3,7,11,13 depending on the form 6k+r, 0 < r < 6. See the link for a proof. LINKS Cino Hilliard, Proof 955..559 is composite. FORMULA S(x)=9*10^(x+1)+ 9 + 50*(10^x-1)/9. PROG (PARI) g(n, r, m) = epeat rrr.. surrounded by 2 m's { for(x=1, n, y=m*10^(x+1)+m+r*10*(10^x-1)/9; print(x", ") ) } CROSSREFS Sequence in context: A031903 A226851 A158410 * A167780 A316338 A257417 Adjacent sequences:  A108900 A108901 A108902 * A108904 A108905 A108906 KEYWORD easy,nonn,base AUTHOR Cino Hilliard, Jul 16 2005 STATUS approved

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Last modified January 24 07:15 EST 2020. Contains 331189 sequences. (Running on oeis4.)