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A163213 Swinging Wilson remainders ((p-1)$ + (-1)^floor((p+2)/2))/p mod p, p prime. Here '$' denotes the swinging factorial function (A056040). 4
1, 1, 1, 3, 1, 6, 9, 13, 12, 2, 19, 2, 5, 36, 6, 19, 43, 11, 47, 67, 39, 41, 70, 12, 17, 83, 88, 81, 25, 53, 91, 97, 106, 79, 43, 39, 7, 29, 73, 6, 79, 115 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

If this is zero, p is a swinging Wilson prime.

REFERENCES

Peter Luschny, "Divide, swing and conquer the factorial and the lcm{1,2,...,n}", preprint, April 2008.

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000

Peter Luschny, Swinging Primes.

EXAMPLE

The swinging Wilson quotient related to the 5th prime is (252+1)/11=23, so the 5th term is 23 mod 11 = 1.

MAPLE

WR := proc(f, r, n) map(p->(f(p-1)+r(p))/p mod p, select(isprime, [$1..n])) end:

A002068 := n -> WR(factorial, p->1, n);

A163213 := n -> WR(swing, p->(-1)^iquo(p+2, 2), n);

MATHEMATICA

sf[n_] := n!/Quotient[n, 2]!^2; a[n_] := (p = Prime[n]; Mod[(sf[p - 1] + (-1)^Floor[(p + 2)/2])/p, p]); Table[a[n], {n, 1, 42}] (* Jean-Fran├žois Alcover, Jun 28 2013 *)

PROG

(PARI) sf(n)=n!/(n\2)!^2

apply(p->sf(p-1)\/p%p, primes(100)) \\ Charles R Greathouse IV, Dec 11 2016

CROSSREFS

Cf. A163211, A002068, A163210.

Sequence in context: A089710 A065918 A020861 * A095066 A169955 A084536

Adjacent sequences:  A163210 A163211 A163212 * A163214 A163215 A163216

KEYWORD

nonn

AUTHOR

Peter Luschny, Jul 24 2009

STATUS

approved

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Last modified June 26 23:21 EDT 2017. Contains 288777 sequences.