This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A177860 Product of the quadratic residues of prime(n). 2
 1, 1, 4, 8, 540, 12960, 1797120, 22619520, 465813504, 267346759680000, 216218419200000, 199658024013127680000, 136256285631578112000000, 12446179270879850496000000, 34611344543529418987929600 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(n) == (-1)^((p+1)/2) (mod p), if p = prime(n) is odd. REFERENCES Carl-Erik Froeberg, On sums and products of quadratic residues, BIT, Nord. Tidskr. Inf.-behandl. 11 (1971) 389-398. LINKS Rahul Gupta, Algorithmic Number Theory, Section 24.5 FORMULA a(n) = (p-1)!/A177861(n), where p = prime(n). EXAMPLE The quadratic residues of prime(4) = 7 are 1, 2, and 4, so a(4) = 1*2*4 = 8. MATHEMATICA Table[ Apply[Times, Flatten[Position[ Table[JacobiSymbol[i, Prime[n]], {i, 1, Prime[n] - 1}], 1]]], {n, 1, 16}] CROSSREFS Cf. A076409 Sum of the quadratic residues of prime(n), A177861 Product of the quadratic nonresidues of prime(n), A163366 Product of the quadratic residues of prime(n) modulo prime(n). Sequence in context: A136386 A260726 A308553 * A013443 A013442 A013441 Adjacent sequences:  A177857 A177858 A177859 * A177861 A177862 A177863 KEYWORD easy,nonn AUTHOR Jonathan Sondow, May 14 2010 STATUS approved

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

Last modified October 14 11:51 EDT 2019. Contains 327997 sequences. (Running on oeis4.)