OFFSET
1,4
COMMENTS
The spread of a permutation p is the sum of i*p(i) over 0 <= i < n, reduced modulo n. - Rintaro Matsuo, Nov 26 2022
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Rintaro Matsuo, Table of n, a(n) for n = 1..40
R. L. Graham, and D. H. Lehmer, On the Permanent of Schur's Matrix, Jour. Australian Math. Soc. 21 no. 4 (series A) (1976), 487-497.
Rintaro Matsuo, Code used to calculate up to a(40)
PROG
(PARI) a(n) = my(v=[1..n], nb=0); forperm(v, p, if (sum(i=1, n-1, Mod(i, n)*p[i]) == 0, nb++)); nb; \\ Michel Marcus, Nov 30 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), May 17 2007
STATUS
approved