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 A113933 (F5,F7,F8,F9,F10,F11,F12,F14) - 10^n = prime where F stands for the Fermat numbers 2^2^x + 1 where x corresponds to 5,7,8,9,10,11,12 and 14. 0
 2, 16, 28, 6, 30, 72, 130, 255 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS This sequence shows that the difference between a composite number and a prime rests on the modification of a single decimal digit. Note that F6 and F13 regarding the Fermat numbers are exceptions to this rule. LINKS EXAMPLE F5 - 10^2 = 4294967197 = prime MATHEMATICA Position[PrimeQ[Table[2^2^5 + 1 - 10^n, {n, 10}]], True] CROSSREFS Sequence in context: A067566 A067555 A108705 * A127871 A242933 A321308 Adjacent sequences:  A113930 A113931 A113932 * A113934 A113935 A113936 KEYWORD nonn AUTHOR Joao Carlos Leandro da Silva (zxawyh66(AT)yahoo.com), Jan 30 2006 STATUS approved

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Last modified June 19 09:39 EDT 2021. Contains 345126 sequences. (Running on oeis4.)