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A121051
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Semiprimes which are sums of 4 but no fewer nonzero squares.
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0
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15, 39, 55, 87, 95, 111, 119, 143, 159, 183, 215, 247, 287, 295
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Semiprime analogue of A007522 Primes of form 8n+7. These semiprimes must all be numbers of the form 4^i(8j+7), i >= 0, j >= 0. However, for positive i, 4^i(8j+7) has more than 2 prime factors (with multiplicity). Hence from Legendre's corollary to Lagrange's Four-Square Theorem, this sequence is precisely Semiprimes of the form 8*k+7.
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CROSSREFS
| A001358 intersect A004215.
Cf. A001358, A004215, A007522.
Sequence in context: A086096 A176257 A055131 * A139042 A020142 A146696
Adjacent sequences: A121048 A121049 A121050 * A121052 A121053 A121054
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KEYWORD
| easy,nonn,less
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AUTHOR
| Jonathan Vos Post (jvospost3(AT)gmail.com), Aug 08 2006
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