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A300329 Number of solutions to +-1 +- 2 +- 3 +- ... +- n == n-1 (mod n). 2
2, 4, 2, 0, 6, 20, 18, 0, 56, 204, 186, 0, 630, 2340, 2182, 0, 7710, 29120, 27594, 0, 99858, 381300, 364722, 0, 1342176, 5162220, 4971008, 0, 18512790, 71582716, 69273666, 0, 260300986, 1010580540, 981706806, 0, 3714566310, 14467258260, 14096302710, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..3333

EXAMPLE

Solutions for n = 7:

--------------------------------------------------------------

1 +2 +3 +4 -5 -6 +7 =   6,         -1 +2 +3 -4 +5 -6 +7 =   6,

1 +2 +3 +4 -5 -6 -7 =  -8,         -1 +2 +3 -4 +5 -6 -7 =  -8,

1 +2 +3 -4 +5 +6 +7 =  20,         -1 +2 -3 +4 +5 +6 +7 =  20,

1 +2 +3 -4 +5 +6 -7 =   6,         -1 +2 -3 +4 +5 +6 -7 =   6,

1 +2 -3 -4 -5 -6 +7 =  -8,         -1 -2 +3 -4 -5 -6 +7 =  -8,

1 +2 -3 -4 -5 -6 -7 = -22,         -1 -2 +3 -4 -5 -6 -7 = -22,

1 -2 +3 -4 -5 +6 +7 =   6,         -1 -2 -3 +4 -5 +6 +7 =   6,

1 -2 +3 -4 -5 +6 -7 =  -8,         -1 -2 -3 +4 -5 +6 -7 =  -8,

1 -2 -3 +4 +5 -6 +7 =   6,

1 -2 -3 +4 +5 -6 -7 =  -8.

PROG

(PARI) a(n) = my (v=vector(n, k, k==1)); for (p=1, n, v = vector(n, k, v[1+(k-1+p)%n]+v[1+(k-1-p)%n])); v[1+(n-1)%n] \\ Rémy Sigrist, Mar 03 2018

CROSSREFS

Cf. A300190, A300328.

Sequence in context: A127278 A335764 A202069 * A094239 A273240 A201316

Adjacent sequences:  A300326 A300327 A300328 * A300330 A300331 A300332

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Mar 03 2018

STATUS

approved

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Last modified August 6 12:33 EDT 2020. Contains 336246 sequences. (Running on oeis4.)