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A141266
Concatenate double factorials.
2
1, 12, 123, 1238, 123815, 12381548, 12381548105, 12381548105384, 12381548105384945, 123815481053849453840, 12381548105384945384010395, 1238154810538494538401039546080, 1238154810538494538401039546080135135
OFFSET
0,2
FORMULA
a(n) = a(n-1)*10^floor(1+log_10(n!!)) + n!!, with a(1)=1.
MAPLE
P:=proc(i) local a, j, k, n; a:=1; print(1); for n from 2 by 1 to i do k:=n; j:=n-2; while j>0 do k:=k*j; j:=j-2; od; a:=a*10^floor(evalf(1+log10(k), 1000))+k; print(a); od; end: P(20);
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Paolo P. Lava, Jun 20 2008
STATUS
approved