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A069113 Squarefree part of C(2n,n), the central binomial numbers: the smallest number such that a(n)*C(2n,n) is a square. 3
1, 2, 6, 5, 70, 7, 231, 858, 1430, 12155, 46189, 176358, 676039, 104006, 44574, 1077205, 66786710, 64822395, 90751353, 353452638, 3829070245, 134564468610, 526024740930, 2287064091, 35830670759, 71661341518, 281132955186, 2483341104143, 1912172650190110 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000

FORMULA

a(n) = A271187(2n,n). - Alois P. Heinz, Apr 01 2016

MAPLE

a:= n-> mul(i[1]^irem(i[2], 2), i=ifactors(binomial(2*n, n))[2]):

seq(a(n), n=0..35);  # Alois P. Heinz, Apr 01 2016

PROG

(PARI) for(n=1, 60, print1(core(binomial(2*n, n)), ", "))

CROSSREFS

Cf. A007913, A271187.

May be the same as A085057.

Sequence in context: A283475 A175350 A085057 * A298329 A009462 A111119

Adjacent sequences:  A069110 A069111 A069112 * A069114 A069115 A069116

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Apr 06 2002

EXTENSIONS

a(0)=1 from Alois P. Heinz, Apr 01 2016

STATUS

approved

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Last modified June 5 18:48 EDT 2020. Contains 334854 sequences. (Running on oeis4.)