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A118330
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a(n-1)*a(n-4) + a(n-2)*a(n-5) + a(n-3)*a(n-6), with a(k<6) = 1.
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0
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1, 1, 1, 1, 1, 1, 3, 5, 9, 17, 65, 385, 3841, 69087, 4559417, 1759931497, 6761656746177, 467149341275385921, 2129929115299135769778433, 3748529338522222733404780820902657
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,7
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COMMENTS
| This is the 3-term analogue of the 2-term recurrence A111288 a(1) = a(2) = a(3) = a(4) = 1. For n>= 5, a(n) = a(n-1)*a(n-3) + a(n-2)*a(n-4). Primes in this sequence include a(n) for n = 6, 7, 9, ... with a(21) and a(22) composite and the sequence growing beyond my ability to efficiently test primality.
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FORMULA
| a(0) = a(1) = a(2) = a(3) = a(4) = a(5) = 1; for n>5: a(n) = a(n-1)*a(n-4) + a(n-2)*a(n-5) + a(n-3)*a(n-6).
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CROSSREFS
| Cf. A111288, A111388.
Sequence in context: A096390 A092264 A135729 * A062221 A074861 A120941
Adjacent sequences: A118327 A118328 A118329 * A118331 A118332 A118333
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KEYWORD
| easy,nonn
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AUTHOR
| Jonathan Vos Post (jvospost3(AT)gmail.com), May 14 2006
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