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Search: id:A038163
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| A038163 |
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G.f.: 1/((1-x)*(1-x^2))^3. |
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+0
11
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| 1, 3, 9, 19, 39, 69, 119, 189, 294, 434, 630, 882, 1218, 1638, 2178, 2838, 3663, 4653, 5863, 7293, 9009, 11011, 13377, 16107, 19292, 22932, 27132, 31892, 37332, 43452, 50388, 58140, 66861, 76551, 87381, 99351, 112651, 127281
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OFFSET
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0,2
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COMMENT
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Number of symmetric nonnegative integer 6 X 6 matrices with sum of elements equal to 4*n, under action of dihedral group D_4 - Vladeta Jovovic (vladeta(AT)Eunet.yu), May 14 2000
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FORMULA
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a(2*k) = (4*k + 5)*binomial(k + 4, 4)/5 = A034263(k); a(2*k + 1) = binomial(k + 4, 4)*(15 + 4*k)/5 = A059599(k), k >= 0.
a(n) = 1/3840*(4*n^5+90*n^4+760*n^3+2970*n^2+5266*n+3285+(-1)^n*(30*n^2+270*n+555)). Recurrence: a(n) = 3*a(n-1)-8*a(n-3)+6*a(n-4)+6*a(n-5)-8*a(n-6)+3*a(n-8)-a(n-9). - Vladeta Jovovic (vladeta(AT)Eunet.yu), Apr 24 2002
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CROSSREFS
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Cf. A008619, A006918, A001753.
Cf. A096338.
Sequence in context: A005994 A080010 A135117 this_sequence A075188 A051894 A095828
Adjacent sequences: A038160 A038161 A038162 this_sequence A038164 A038165 A038166
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KEYWORD
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nonn
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AUTHOR
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njas
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