|
Search: id:A008749
|
|
|
| A008749 |
|
Expansion of (1+x^6)/(1-x)/(1-x^2)/(1-x^3). |
|
+0
1
|
|
| 1, 1, 2, 3, 4, 5, 8, 9, 12, 15, 18, 21, 26, 29, 34, 39, 44, 49, 56, 61, 68, 75, 82, 89, 98, 105, 114, 123, 132, 141, 152, 161, 172, 183, 194, 205, 218, 229, 242, 255, 268, 281, 296, 309, 324, 339, 354, 369
(list; graph; listen)
|
|
|
OFFSET
|
0,3
|
|
|
COMMENT
|
Conjecture: For n >= 1, A067628(a(n+2)) appears for the first time in A067628. Equivalently, A067628(a(n+2)) is the first T such that the minimal perimeter of polyiamonds of T triangles is a(n+2). - Winston C. Yang (winston(AT)cs.wisc.edu), Feb 05 2002
|
|
FORMULA
|
Conjecture: Let b(n>=0) = (0, 1, 1, 1, 1, 3, 1, 3, 3, 3, 3, 5, 3, 5, 5, 5, 5, 7, 3, ...). Equivalently, let b(0) = 0, b(n>=1) = 2*floor((n-1)/6) + 1 + (2 if n+1=0 mod 6; 0 else). Then a(0) = 1, a(n>=1) = a(n-1) + b(n-1). - Winston C. Yang (winston(AT)cs.wisc.edu), Feb 05 2002
|
|
EXAMPLE
|
Let n = 8. Then a(n+2) = a(10) = 18. Note A067628(18) = 12 and is the first appearance of 12 in A067628. Equivalently, 12 is the first T such that the min perimeter of polyiamonds of T triangles is 18.
|
|
CROSSREFS
|
Cf. A067628.
Sequence in context: A083132 A118956 A109850 this_sequence A029000 A042962 A027584
Adjacent sequences: A008746 A008747 A008748 this_sequence A008750 A008751 A008752
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
njas
|
|
|
Search completed in 0.002 seconds
|
