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 A077169 Initial terms of rows of A077168. 6
 1, 2, 4, 7, 11, 15, 20, 26, 33, 41, 50, 60, 71, 83, 96, 110, 125, 141, 158, 176, 195, 215, 236, 258, 281, 305, 330, 356, 383, 411, 440, 470, 501, 533, 566, 600, 635, 671, 708, 746, 785, 825, 866, 908, 951, 995, 1040, 1086, 1133, 1181, 1230, 1280, 1331, 1383 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS G. C. Greubel, Table of n, a(n) for n = 0..5000 Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA For n>3, a(n) = (n^2-n+10)/2. From G. C. Greubel, Jul 13 2017: (Start) a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3), n >= 7. G.f.: (1-x+x^2-x^5 + x^6)/(1-x)^3. E.g.f.: (1/2)*(x^2 + 10)*exp(x) - 4 - 3*x + x^2 - x^3/6. (End) Sum_{n>=0} 1/a(n) = 1177/840 + 2*Pi*tanh(sqrt(39)*Pi/2)/sqrt(39). - Amiram Eldar, Dec 13 2022 MATHEMATICA Join[{1, 2, 4, 7}, Table[(n^2 - n + 10)/2, {n, 4, 50}]] (* G. C. Greubel, Jul 13 2017 *) PROG (PARI) concat([1, 2, 4, 7], for(n=4, 50, print1((n^2 - n +10)/2, ", "))) \\ G. C. Greubel, Jul 13 2017 CROSSREFS Cf. A077168, A077170. Sequence in context: A036700 A025719 A025696 * A094277 A263995 A293239 Adjacent sequences: A077166 A077167 A077168 * A077170 A077171 A077172 KEYWORD nonn,easy AUTHOR Amarnath Murthy, Nov 01 2002 EXTENSIONS More terms from Sascha Kurz, Feb 10 2003 STATUS approved

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Last modified August 2 19:53 EDT 2024. Contains 374875 sequences. (Running on oeis4.)