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 A017197 a(n) = 9*n + 3. 15
 3, 12, 21, 30, 39, 48, 57, 66, 75, 84, 93, 102, 111, 120, 129, 138, 147, 156, 165, 174, 183, 192, 201, 210, 219, 228, 237, 246, 255, 264, 273, 282, 291, 300, 309, 318, 327, 336, 345, 354, 363, 372, 381, 390, 399, 408, 417, 426, 435, 444, 453, 462, 471, 480 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Numbers whose digital root is 3. - Cino Hilliard, Dec 26 2006 a(n)^2 = A017198(n). - Reinhard Zumkeller, Jul 13 2010 LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 Tanya Khovanova, Recursive Sequences Luis Manuel Rivera, Integer sequences and k-commuting permutations, arXiv preprint arXiv:1406.3081 [math.CO], 2014-2015. Index entries for linear recurrences with constant coefficients, signature (2,-1). FORMULA a(n) = a(n-1) + 9. a(n) = 3*A016777(n). a(n) = A092292(n) + A092293(n) + A092296(n). From Philippe Deléham, Mar 10 2004: (Start) Sum_{n>=0} (-1)^n / a(n) = (Pi / sqrt(3) + log(2))/9. G.f.: 3*(1+2*x)/(1-x)^2. (End) a(n) = 3*(6*n-1) - a(n-1) with a(0)=3. - Vincenzo Librandi, Nov 20 2010 E.g.f.: 3*(1 + 3*x)*exp(x). - G. C. Greubel, Dec 03 2019 MAPLE seq(9*n+3, n=0..60); # G. C. Greubel, Dec 03 2019 MATHEMATICA 3*(3*Range[60] -2) (* G. C. Greubel, Dec 03 2019 *) PROG (PARI) vector(60, n, 3*(3*n-2) ) \\ G. C. Greubel, Dec 03 2019 (Sage) [i+3 for i in range(480) if gcd(i, 9) == 9] # Zerinvary Lajos, May 20 2009 (Haskell) a017197 = (+ 3) . (* 9) a017197_list = [3, 12 ..]  -- Reinhard Zumkeller, Jun 04 2015 (MAGMA) [9*n+3: n in [0..60]]; // G. C. Greubel, Dec 03 2019 (GAP) List([0..60], n-> 9*n+3); # G. C. Greubel, Dec 03 2019 CROSSREFS Cf. A092292, A092293, A092296. Cf. sequences with general form q*(q*n+1): A016825 (q=2), this sequence (q=3), A119413 (q=4), ... - Vladimir Joseph Stephan Orlovsky, Feb 16 2009 Cf. A016777. Sequence in context: A074276 A055041 A061819 * A051369 A069538 A052217 Adjacent sequences:  A017194 A017195 A017196 * A017198 A017199 A017200 KEYWORD nonn,easy AUTHOR EXTENSIONS More terms from Cino Hilliard, Dec 26 2006 STATUS approved

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Last modified October 20 23:28 EDT 2020. Contains 337910 sequences. (Running on oeis4.)