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Search: id:A076505
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| A076505 |
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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. |
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+0
2
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| 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; listen)
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OFFSET
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1,2
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COMMENT
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There are many terms that are not Niven/Harshad numbers. The first is a(15)=2985984, whose digits sum to 45, which does not divide evenly. [From T. D. Noe (noe(AT)sspectra.com), Oct 26 2009]
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FORMULA
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For n>4, a(n) = a(n-3)*4!. Also, every a(n) is a Niven/Harshad number. - 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].
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PROGRAM
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(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))
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CROSSREFS
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Cf. A076506.
Sequence in context: A053900 A126977 A102237 this_sequence A129345 A125019 A024976
Adjacent sequences: A076502 A076503 A076504 this_sequence A076506 A076507 A076508
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KEYWORD
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nonn
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AUTHOR
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Jon Perry (perry(AT)globalnet.co.uk), Oct 15 2002
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EXTENSIONS
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More terms from Rob Hoogers (chimera(AT)chimera.fol.nl), Jun 27 2004
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