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REFERENCES
| Comtet, L. Advanced Combinatorics: The Art of Finite and Infinite Expansions, rev. enl. ed. Dordrecht, Netherlands: Reidel, p. 56, 1974.
Graham, R. L.; Knuth, D. E.; and Patashnik, O. Exercise 7.50 in Concrete Mathematics: A Foundation for Computer Science, 2nd ed. Reading, MA: Addison-Wesley, 1994.
Motzkin, T. "Relations Between Hypersurface Cross Ratios and a Combinatorial Formula for Partitions of a Polygon for Permanent Preponderance and for Non-Associative Products." Bull. Amer. Math. Soc. 54, 352-360, 1948.
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EXAMPLE
| a(1) = 4279 because it is super-Catalan and semiprime, since 4279 = 11 x 389.
a(2) = 2646723 because it is super-Catalan and 2646723 = 3 x 882241.
Similarly:
a(3) = 55909013009 = 41263 x 1354943.
a(4) = 1618362158587 = 24413 x 66290999.
a(5) = 47574827600981 = 3253 x 14624908577.
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