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 A082149 A transform of C(n,2). 2
 0, 0, 1, 6, 30, 140, 615, 2562, 10220, 39384, 147645, 541310, 1948650, 6908772, 24180611, 83702010, 286978200, 975725744, 3293074233, 11041484022, 36804946550, 122037454140, 402723598431, 1323234680306, 4330586226180 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS Represents the mean of C(n,2) with its second binomial transform. Binomial transform of A080929 (preceded by two zeros). LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (12,-57,136,-171,108,-27). FORMULA a(n) = C(n, 2)*(3^(n-2) + 1)/2. G.f.: (x^2/(1-3x)^3+x^2/(1-x)^3)/2. G.f.: x^2(14*x^3-15*x^2+6*x-1)/((1-x)^3*(3*x-1)^3). E.g.f.: x^2*exp(2*x)*cosh(x)/2. MATHEMATICA CoefficientList[Series[(x^2/(1-3*x)^3 + x^2/(1-x)^3)/2, {x, 0, 50}], x] (* or *) Table[Binomial[n, 2]*(1 + 3^(n-2))/2, {n, 0, 30}] (* G. C. Greubel, Feb 10 2018 *) PROG (PARI) for(n=0, 30, print1(binomial(n, 2)*(1 + 3^(n-2))/2, ", ")) \\ G. C. Greubel, Feb 10 2018 (MAGMA) [Binomial(n, 2)*(1 + 3^(n-2))/2: n in [0..30]]; // G. C. Greubel, Feb 10 2018 CROSSREFS Cf. A082150, A000217, A027472. Sequence in context: A001334 A125316 A092439 * A002457 A137400 A220830 Adjacent sequences:  A082146 A082147 A082148 * A082150 A082151 A082152 KEYWORD easy,nonn AUTHOR Paul Barry, Apr 07 2003 STATUS approved

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Last modified August 3 20:08 EDT 2020. Contains 336201 sequences. (Running on oeis4.)