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A069268 Greatest common divisor of n! and n*(n+1)/2. 4
1, 1, 6, 2, 15, 3, 28, 36, 45, 5, 66, 6, 91, 105, 120, 8, 153, 9, 190, 210, 231, 11, 276, 300, 325, 351, 378, 14, 435, 15, 496, 528, 561, 595, 630, 18, 703, 741, 780, 20, 861, 21, 946, 990, 1035, 23, 1128, 1176, 1225, 1275, 1326 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Paolo P. Lava, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = if n>1 and n+1 is prime then n/2 else n*(n+1)/2.

MATHEMATICA

Table[GCD[n!, (n(n+1))/2], {n, 60}] (* Harvey P. Dale, Oct 14 2013 *)

CROSSREFS

Cf. A000142, A000217, A000040.

Cf. A090585, A090586.

Sequence in context: A080977 A095951 A116420 * A082155 A128225 A136398

Adjacent sequences:  A069265 A069266 A069267 * A069269 A069270 A069271

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Apr 14 2002

STATUS

approved

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Last modified August 8 23:02 EDT 2020. Contains 336300 sequences. (Running on oeis4.)