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A042970 a(n) = binomial(n, floor(n/2)) mod n. 1
0, 0, 0, 2, 0, 2, 0, 6, 0, 2, 0, 0, 0, 2, 0, 6, 0, 2, 0, 16, 0, 2, 0, 4, 0, 2, 0, 20, 0, 0, 0, 6, 0, 2, 0, 24, 0, 2, 0, 20, 0, 6, 0, 28, 0, 2, 0, 12, 0, 2, 0, 32, 0, 20, 0, 0, 0, 2, 0, 4, 0, 2, 0, 6, 0, 42, 0, 40, 0, 42, 0, 52, 0, 2, 0, 44, 0, 20, 0, 20, 0, 2, 0, 0, 0, 2, 0, 48, 0, 0, 0, 52, 0, 2, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Value 924 occurs for 248 times among the first 20000 terms (see the horizontal stripe near y=1000 in the scatter plot). Where does it originate from? - Antti Karttunen, Feb 13 2019

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..20000

EXAMPLE

a(10) = binomial(10,5) mod 10 = 252 mod 10 = 2.

MAPLE

a:=n->modp(binomial(n, floor(n/2)), n): seq(a(n), n=1..110); # Muniru A Asiru, Feb 17 2019

MATHEMATICA

Table[Mod[Binomial[n, Floor[n/2]], n], {n, 1, 110}] (* G. C. Greubel, Feb 17 2019 *)

PROG

(PARI) a(n) = binomial(n, n\2) % n; \\ Michel Marcus, May 14 2018

(MAGMA) [Binomial(n, Floor(n/2)) mod n: n in [1..110]]; // G. C. Greubel, Feb 17 2019

(Sage) [mod(binomial(n, floor(n/2)), n) for n in (1..110)] # G. C. Greubel, Feb 17 2019

CROSSREFS

Cf. A001405, A020475.

Sequence in context: A327371 A037228 A002117 * A158327 A136581 A175950

Adjacent sequences:  A042967 A042968 A042969 * A042971 A042972 A042973

KEYWORD

nonn,look

AUTHOR

Labos Elemer

EXTENSIONS

Name corrected by Jon E. Schoenfield, May 13 2018

STATUS

approved

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Last modified February 27 04:09 EST 2020. Contains 332299 sequences. (Running on oeis4.)