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A118455
a(1)=1, a(n) = Product_{k=2..n} P(k), where P(k) is the largest prime <= k.
6
1, 2, 6, 18, 90, 450, 3150, 22050, 154350, 1080450, 11884950, 130734450, 1699547850, 22094122050, 287223586650, 3733906626450, 63476412649650, 1079099015044050, 20502881285836950, 389554744430902050
OFFSET
1,2
LINKS
EXAMPLE
a(6)=450 because the largest primes that do not exceed 2,3,4,5 and 6 are, respectively 2,3,3,5 and 5, having product 2*3*3*5*5=450.
MAPLE
a:=proc(n) if n=1 then 1 else product(prevprime(k+1), k=2..n) fi end: seq(a(n), n=1..23); # Emeric Deutsch, Apr 30 2006
MATHEMATICA
FoldList[Times, 1, Table[Prime@ PrimePi@ k, {k, 2, 20}]] (* Michael De Vlieger, Aug 21 2017 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Leroy Quet, Apr 28 2006
EXTENSIONS
More terms from Emeric Deutsch, Apr 30 2006
STATUS
approved