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 A064394 Exponent of highest power of 2 dividing n! equals the largest prime < n. 3
 4, 5, 8, 9, 22, 23, 26, 27, 32, 33, 50, 51, 56, 57, 70, 71, 76, 77, 82, 83, 94, 95, 100, 101, 112, 113, 118, 119, 128, 129, 134, 135, 176, 177, 186, 187, 196, 197, 266, 267, 274, 275, 280, 281, 296, 297, 342, 343, 352, 353, 358, 359, 364, 365, 372, 373, 386, 387 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS [n/2]+[n/4]+[n/8]+[n/16]+... = prevprime(n). LINKS Harvey P. Dale, Table of n, a(n) for n = 0..1000 EXAMPLE 8!=2^7*3^2*5*7, 23!=2^19*3^9*5^4*7^3*11^2*13*17*19*23. MAPLE for n from 3 to 10^3 do if sum(floor(n/(2^i)), i=1..15) = prevprime(n) then printf(`%d, `, n) fi; od: MATHEMATICA Select[Range[400], IntegerExponent[#!, 2]==NextPrime[#, -1]&] (* Harvey P. Dale, Sep 24 2013 *) CROSSREFS Cf. A011371, A007917. Sequence in context: A228012 A067271 A268128 * A346457 A141220 A340762 Adjacent sequences:  A064391 A064392 A064393 * A064395 A064396 A064397 KEYWORD nonn AUTHOR Vladeta Jovovic, Sep 29 2001 EXTENSIONS More terms from James A. Sellers, Oct 01 2001 STATUS approved

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Last modified July 26 08:42 EDT 2021. Contains 346294 sequences. (Running on oeis4.)