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A054552
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a(n) = 4*n^2 - 3*n + 1.
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56
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1, 2, 11, 28, 53, 86, 127, 176, 233, 298, 371, 452, 541, 638, 743, 856, 977, 1106, 1243, 1388, 1541, 1702, 1871, 2048, 2233, 2426, 2627, 2836, 3053, 3278, 3511, 3752, 4001, 4258, 4523, 4796, 5077, 5366, 5663, 5968, 6281, 6602, 6931, 7268, 7613, 7966, 8327
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OFFSET
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0,2
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COMMENTS
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Also indices in any square spiral organized like A054551.
Equals binomial transform of [1, 1, 8, 0, 0, 0, ...]. - Gary W. Adamson, May 11 2008
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LINKS
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FORMULA
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G.f.: (1 - x + 8*x^2)/(1-x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3); a(0)=1, a(1)=2, a(2)=11. - Harvey P. Dale, Oct 10 2011
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EXAMPLE
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The spiral begins:
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197-196-195-194-193-192-191-190-189-188-187-186-185-184-183
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198 145-144-143-142-141-140-139-138-137-136-135-134-133 182
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199 146 101-100--99--98--97--96--95--94--93--92--91 132 181
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200 147 102 65--64--63--62--61--60--59--58--57 90 131 180
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201 148 103 66 37--36--35--34--33--32--31 56 89 130 179
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202 149 104 67 38 17--16--15--14--13 30 55 88 129 178
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203 150 105 68 39 18 5---4---3 12 29 54 87 128 177
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204 151 106 69 40 19 6 1---2 11 28 53 86 127 176
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205 152 107 70 41 20 7---8---9--10 27 52 85 126 175
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206 153 108 71 42 21--22--23--24--25--26 51 84 125 174
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207 154 109 72 43--44--45--46--47--48--49--50 83 124 173
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208 155 110 73--74--75--76--77--78--79--80--81--82 123 172
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209 156 111-112-113-114-115-116-117-118-119-120-121-122 171
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210 157-158-159-160-161-162-163-164-165-166-167-168-169-170
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211-212-213-214-215-216-217-218-219-220-221-222-223-224-225
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MAPLE
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MATHEMATICA
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PROG
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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