A225067 Least heptagonal (7-gonal) number that is the product of n heptagonal numbers greater than 1.

7, 6426, 35224, 2077992, 3610893055, 14209771072, 118896888880, 6400213601782, 22535310978496008, 22535310978496008, 2418562185097611420000, 2462278542548750181849600

Offset: 1

Author

T. D. Noe, May 01 2013

Keywords

• nonn
• more

Examples

			Let hep(n) = n*(5n-3)/2. Then
a(1) = 7 = hep(2).
a(2) = 6426 = hep(51) = hep(4) * hep(9).
a(3) = 35224 = hep(119) = hep(2) * hep(4) * hep(8).
a(4) = 2077992 = hep(912) = hep(2)^2 * hep(3) * hep(31).
a(5) = 3610893055 = hep(38005) = hep(2)^3 * hep(5) * hep(277).
a(6) = 14209771072 = hep(75392) = hep(2)^4 * hep(31) * hep(32).
		

Links

• Lars Blomberg, Table of n, a(n) with solutions for n=1..12

Crossrefs

Cf. A000566 (heptagonal numbers).

Cf. A212616, A212617, A225066-A225070 (3-, 5- to 10-gonal cases).

Extensions

Corrected a(6) and added a(7)-a(12) by Lars Blomberg, Sep 21 2013