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 A163467 a(n) = floor(p/2) * floor(floor(p/2)/2) * floor(floor(floor(p/2)/2)/2) * ... * 1, where p=prime(n). 2
 1, 1, 2, 3, 10, 18, 64, 72, 110, 294, 315, 1296, 2000, 2100, 2530, 6084, 8526, 9450, 33792, 38080, 46656, 53352, 82000, 106480, 248832, 270000, 275400, 322452, 341172, 460992, 615195, 2129920, 2515456, 2552448, 3548448, 3596400, 4161456 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Cumulative product of the residuals of a repeated shift-right operation on the base-2 representation of prime(n). LINKS G. C. Greubel, Table of n, a(n) for n = 1..5000 EXAMPLE For n=6, p=13, the intermediate factors are floor(13/2)=6, floor(6/2)=3, floor(3/2)=1, which yield a(6)=6*3*1=18. For n=7, p=17, floor(17/2)=8, floor(8/2)=4, floor(4/2)=2, floor(2/2)=1, which yield a(7)=8*4*2*1=64. MATHEMATICA lst={}; Do[p=Prime[n]; s=1; While[p>1, p=IntegerPart[p/2]; s*=p; ]; AppendTo[lst, s], {n, 5!}]; lst Table[Times@@Rest[NestWhileList[Floor[#/2]&, Prime[n], #>1&]], {n, 40}] (* Harvey P. Dale, Jul 05 2019 *) PROG (PARI) a(n) = my(p=prime(n), k=1); while(p!=1, k *= p\2; p = p\2); k; \\ Michel Marcus, Jul 26 2017 CROSSREFS Cf. A098844. Sequence in context: A298345 A057507 A233895 * A143045 A156909 A215121 Adjacent sequences:  A163464 A163465 A163466 * A163468 A163469 A163470 KEYWORD nonn,easy AUTHOR Vladimir Joseph Stephan Orlovsky, Jul 28 2009 EXTENSIONS More divisions and primes mentioned in the definition by R. J. Mathar, Aug 02 2009 STATUS approved

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Last modified May 18 16:07 EDT 2021. Contains 343995 sequences. (Running on oeis4.)