A100592 Least positive integer that can be represented as the sum of exactly two semiprimes in exactly n ways.

1, 8, 18, 30, 43, 48, 60, 72, 91, 108, 132, 155, 120, 144, 192, 168, 216, 236, 227, 180, 320, 340, 240, 252, 348, 300, 324, 336, 488, 484, 456, 396, 614, 360, 524, 548, 706, 468, 536, 656, 628, 420, 624, 576, 612, 588, 540, 600, 648, 768, 732, 800, 832, 660

Offset: 0

Author

Jonathan Vos Post, Nov 30 2004

Keywords

• easy
• nonn

Comments

A072931(a(n)) = n and A072931(m) < n for m < a(n). [From Reinhard Zumkeller, Jan 21 2010]

Examples

			a(0) = 1 because 1 is the smallest positive integer that cannot be represented as sum of two semiprimes (since 4 is the smallest semiprime). a(1) = 8 because 8 is the smallest such sum of two semiprimes: 4 + 4. Similarly a(2) = 18 because 18 = 14 + 4 = 9 + 9 where {4,9,14} are semiprimes and there is no third such sum for 18.
		

Links

• Reinhard Zumkeller and Zak Seidov, Table of n, a(n) for n = 0..1000 (Terms 0-250 from Reinhard Zumkeller)

Crossrefs

Cf. A001358, A076768, A100570, A072966.

Formula

a(n) = min{i such that i = A001358(j) + A001358(k) in n ways}.