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A056234
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Form an array with 3 rows: row 1 begins with 1; all rows are increasing; each entry is sum of 2 entries above it; each number appears at most once; smallest unused number is appended to first row if possible. Sequence gives numbers not used.
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8
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5, 24, 29, 42, 72, 90, 93, 112, 120, 125, 138, 158, 172, 175, 192, 197, 200, 205, 208, 213, 218, 230, 235, 264, 282, 285, 302, 305, 310, 321, 324, 329, 333, 364, 372, 375, 378, 386, 416, 430, 439, 452, 455, 477, 496, 504, 509, 522, 542, 556
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OFFSET
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1,1
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LINKS
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EXAMPLE
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Array begins
1 2 4 7 8 10 12 ...
.3 6 11 15 18 ...
. 9 17 26 33 ...
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PROG
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(Haskell)
a056234 n = a056234_list !! (n-1)
a056234_list = notUsed 1 a056231_list a056232_list a056233_list where
notUsed x us'@(u:us) vs'@(v:vs) ws'@(w:ws)
| x == u = notUsed (x + 1) us vs' ws'
| x == v = notUsed (x + 1) us' vs ws'
| x == w = notUsed (x + 1) us' vs' ws
| otherwise = x : notUsed (x + 1) us' vs' ws'
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CROSSREFS
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KEYWORD
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nonn,nice,easy
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AUTHOR
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STATUS
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approved
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