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A048477
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a(n) = T(5,n), array T given by A048472.
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2
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1, 7, 25, 73, 193, 481, 1153, 2689, 6145, 13825, 30721, 67585, 147457, 319489, 688129, 1474561, 3145729, 6684673, 14155777, 29884417, 62914561, 132120577, 276824065, 578813953, 1207959553, 2516582401, 5234491393, 10871635969, 22548578305, 46707769345
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OFFSET
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0,2
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COMMENTS
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n-th difference of a(n), a(n-1), ..., a(0) is (6, 12, 18, ...).
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LINKS
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FORMULA
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a(n) = 6*n * 2^(n-1) + 1.
G.f.: (1 + 2*x - 2*x^2) / ((1 - x) * (1 - 2*x)^2).
a(n) = 5*a(n-1)-8*a(n-2)+4*a(n-3) for n>2. - Colin Barker, Feb 18 2016
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PROG
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(PARI) {a(n) = if( n<0, 0, 3 * n * 2^n + 1)}; /* Michael Somos, May 13 2014 */
(PARI) Vec((1+2*x-2*x^2)/((1-x)*(1-2*x)^2) + O(x^40)) \\ Colin Barker, Feb 18 2016
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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