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A100259 Coefficient of x^2 in 2n-th normalized Legendre polynomial. 1
3, -30, 105, -1260, 3465, -18018, 45045, -875160, 2078505, -9699690, 22309287, -202811700, 456326325, -2035917450, 4508102925, -158685222960, 347123925225, -1511010027450, 3273855059475, -28258538408100 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..20.

EXAMPLE

Example: Legendre(12) = (676039x^12 - 1939938x^10 + 2078505x^8 - 1021020x^6 + 225225x^4 - 18018x^2 + 231)/1024, hence a(6) = -18018. - Neven Juric

PROG

(PARI) a(n) = polcoeff(pollegendre(2*n, x), 2)*2^valuation((2*n)!, 2) \\ Michel Marcus, May 29 2013

CROSSREFS

3rd column (without zeros) of triangle A100258.

Sequence in context: A180816 A308402 A035328 * A031205 A225018 A221516

Adjacent sequences:  A100256 A100257 A100258 * A100260 A100261 A100262

KEYWORD

sign

AUTHOR

Ralf Stephan, Nov 13 2004

EXTENSIONS

Definition corrected by Neven Juric, Jan 10 2009

STATUS

approved

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Last modified February 18 21:19 EST 2020. Contains 332028 sequences. (Running on oeis4.)