A225070 Least decagonal (10-gonal) number that is the product of n decagonal numbers greater than 1.

10, 69300, 9729720, 4257000, 967412160, 4104100000, 1408951239696000, 59860503846000000, 1542547619019487080000, 39054496014386012160000, 450510331438947780000000

Offset: 1

Author

T. D. Noe, May 01 2013

Keywords

• nonn
• more

Examples

			Let dec(n) = n*(4n-3). Then
a(1) = 10 = dec(2).
a(2) = 69300 = dec(132) = dec(2) * dec(42).
a(3) = 9729720 = dec(1560) = dec(3) * dec(4) * dec(42).
a(4) = 4257000 = dec(1032) = dec(2)^3 * dec(33).
a(5) = 967412160 = dec(15552) = dec(2) * dec(3) * dec(4) * dec(8) * dec(9).
a(6) = 4104100000 = dec(32032) = dec(2)^3 * dec(4) * dec(7) * dec(11).
		

Links

• Lars Blomberg, Table of n, a(n) with solutions for n=1..11

Crossrefs

Cf. A001107 (decagonal numbers).

Cf. A212616, A212617, A225066-A225069 (3-, 5- to 9-gonal cases).

Extensions

Corrected a(6) and added a(7)-a(11) by Lars Blomberg, Sep 20 2013