A001684 From a continued fraction.

1, 1, 1, 1, 2, 6, 30, 390, 32370, 81022110, 79098077953830, 2499603048957386233742790, 6399996109983215106481566902449146981585570, 1296147136591533261616288032775924136752630487513536584267056282299509616710

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

References

• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• John Cerkan, Table of n, a(n) for n = 0..17
• V. C. Harris, Another proof of the infinitude of primes, Amer. Math. Monthly, 63 (1956), 711.

Formula

a(0) = a(1) = a(2) = 1, a(n) = Product_{k=0..n-3} A001685(k) for n >= 3. - Sean A. Irvine, Nov 13 2012

Extensions

One more term from Sean A. Irvine, Nov 13 2012