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 A076505 3 people at a party are saying Hello to each other. Person 1 says Hello. Person 2 counts the times Hello has been said and says Hello twice that number. Person 3 says Hello 3 times the sum of Hello's and then it is Person 1 again. This is how many Hello's each person says. 1
 1, 2, 9, 12, 48, 216, 288, 1152, 5184, 6912, 27648, 124416, 165888, 663552, 2985984, 3981312, 15925248, 71663616, 95551488, 382205952, 1719926784, 2293235712, 9172942848, 41278242816, 55037657088, 220150628352, 990677827584 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Index entries for linear recurrences with constant coefficients, signature (0,0,24). FORMULA For n>4, a(n) = a(n-3)*4!. - Rob Hoogers (chimera(AT)chimera.fol.nl), Jun 27 2004. a(n) = 2^i*3^j, with i=A064429(n-1), j=[n/3]+[n%3==0]. G.f.: x*(1-x)*(1+3*x+12*x^2)/(1-24*x^3). - Colin Barker, Jun 07 2012 PROG (PARI) mod 3(n)=if (i%3==0, 3, i%3) s=1; for (i=2, 30, print1(s*mod 3(i), ", "); s=s+s*mod 3(i)) CROSSREFS Cf. A076506. Sequence in context: A126977 A102237 A324571 * A218073 A129345 A216350 Adjacent sequences:  A076502 A076503 A076504 * A076506 A076507 A076508 KEYWORD nonn,easy AUTHOR Jon Perry, Oct 15 2002 EXTENSIONS More terms from Rob Hoogers (chimera(AT)chimera.fol.nl), Jun 27 2004 An incorrect comment was deleted, Aug 02 2010 STATUS approved

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Last modified September 18 23:17 EDT 2020. Contains 337175 sequences. (Running on oeis4.)