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A100592 Least positive integer that can be represented as the sum of exactly two semiprimes in exactly n ways. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

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

LINKS

Reinhard Zumkeller and Moshe Levin, Table of n, a(n) for n = 0..1000 (Terms 0-250 from Reinhard Zumkeller)

FORMULA

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

EXAMPLE

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.

CROSSREFS

Cf. A001358, A076768, A100570, A072966.

Sequence in context: A084394 A085248 A092163 * A028563 A171523 A120091

Adjacent sequences:  A100589 A100590 A100591 * A100593 A100594 A100595

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post, Nov 30 2004

STATUS

approved

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Last modified November 20 21:20 EST 2014. Contains 249754 sequences.