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A083487
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Triangle read by rows: T(r,c) = 2*r*c + l + c (1 <= c <= l).
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8
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4, 7, 12, 10, 17, 24, 13, 22, 31, 40, 16, 27, 38, 49, 60, 19, 32, 45, 58, 71, 84, 22, 37, 52, 67, 82, 97, 112, 25, 42, 59, 76, 93, 110, 127, 144, 28, 47, 66, 85, 104, 123, 142, 161, 180, 31, 52, 73, 94, 115, 136, 157, 178, 199, 220, 34, 57, 80, 103, 126, 149
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| T(r,c) gives number of edges (of unit length) in a c X r grid.
The values 2*T(r,c)+1 = (2*r+1)*(2*c+1) are nonprime and therefore in A047845.
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EXAMPLE
| Triangle begins:
4,
7,12,
10,17,24,
13,22,31,40,
16,27,38,49,60,
...
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CROSSREFS
| Cf. A082652, A083003. See A151890 for another version.
Sequence in context: A061956 A178939 A072732 * A158937 A092572 A092574
Adjacent sequences: A083484 A083485 A083486 * A083488 A083489 A083490
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KEYWORD
| nonn,tabl
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AUTHOR
| Artemario Tadeu Medeiros da Silva (artemario(AT)uol.com.br), Jun 09 2003
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EXTENSIONS
| Edited by N. J. A. Sloane, Jul 23 2009
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