The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60, we have over 367,000 sequences, and we’ve crossed 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A224746 a(n) = (Product_{d=1..n-1} (2^d-1)) mod (2^n-1). 1
 0, 1, 3, 6, 5, 0, 7, 60, 301, 837, 11, 2835, 13, 11811, 13454, 2040, 17, 179361, 19, 639375, 1082802, 2818719, 23, 12878775, 28142451, 44845725, 131853841, 161290635, 29, 911545173, 31, 1048560, 4862374202, 11455474329, 26924001270, 62380858995, 37 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS E. Vantieghem proved that a(n) = n if and only if n is an odd prime (see link). LINKS Alois P. Heinz, Table of n, a(n) for n = 1..1000 E. Vantieghem, On a congruence only holding for primes, Indagationes Mathematicae, Volume 2, Issue 2, 17 June 1991, pp. 253-255. MAPLE a:= proc(n) local d, m, r; r, m:= 1, 2^n-1; for d to n-1 do r:= irem(r*(2^d-1), m) od; irem(r, m) end: seq(a(n), n=0..40); # Alois P. Heinz, Apr 17 2013 MATHEMATICA Table[Mod[Product[2^d-1, {d, 1, n-1}], 2^n-1], {n, 1, 37}] (* Geoffrey Critzer, Sep 28 2013 *) PROG (PARI) a(n) = prod(d=1, n-1, 2^d-1) % (2^n-1) \\ Michel Marcus, Apr 17 2013 CROSSREFS Cf. A219732. Sequence in context: A009782 A294670 A016615 * A296226 A296222 A295999 Adjacent sequences: A224743 A224744 A224745 * A224747 A224748 A224749 KEYWORD nonn AUTHOR Michel Marcus, Apr 17 2013 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 2 04:17 EST 2023. Contains 367506 sequences. (Running on oeis4.)