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Search: id:A100591
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| A100591 |
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Least positive integer that can be represented as sum of semiprime and a triangular number in exactly n ways. Triangular numbers include t(0)=0 and (1)=1. |
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+0
1
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| 1, 4, 7, 10, 35, 25, 49, 61, 121, 140, 211, 268, 224, 392, 472, 517, 565, 529, 707, 1006, 1039, 994, 1213, 989, 1274, 1717, 1769, 1822, 2047, 2272, 2419, 2573, 2642, 3029, 3149, 3152, 3848, 3359, 4199, 4019, 4307, 4847, 5027, 4877, 5492, 6077
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Computed by Ray Chandler.
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FORMULA
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a(n) = min(i such that i = A001358(j) + A000217(k) in n ways).
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EXAMPLE
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a(0) = 1 because 1 is the smallest positive integer that cannot be represented as sum of semiprime and a triangular number (since 4 is the smallest semiprime). a(1) = 4 because 4 is the smallest such sum, namely semiprime(1)=4 + t(0)=0. Similarly a(2) = 7 because 7 = 4 + 3 and 7 = 6 + 1, where 4 and 6 are semiprimes, 3 and 1 are triangular.
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CROSSREFS
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Cf. A000217, A001358, A076768, A100570.
Sequence in context: A032818 A123986 A088405 this_sequence A135262 A061515 A071084
Adjacent sequences: A100588 A100589 A100590 this_sequence A100592 A100593 A100594
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Nov 30 2004
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