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A141579
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Numbers n such that the arithmetic mean of the first n tribonacci numbers A000073 is an integer.
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0
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1, 2, 47, 53, 94, 103, 106, 163, 199, 206, 257, 269, 311, 326, 397, 398, 401, 419, 421, 499, 514, 538, 587, 599, 617, 622, 683, 757, 773, 794, 802, 838, 842, 863, 883, 907, 911, 929, 991, 998, 1021, 1087, 1109, 1123, 1174, 1181, 1198, 1210, 1234, 1237, 1291
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Numbers in this sequence but not in A140973 are 2021 and 2090 (but no others below 8400). - E. Deutsch, Aug 19 2008.
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FORMULA
| {n: n | A008937(n-2)}.
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MAPLE
| A000073 := proc(n) option remember ; if n <= 1 then 0 ; elif n =2 then 1 ; else procname(n-1)+procname(n-2)+procname(n-3) ; fi; end: A008937 := proc(n) option remember ; add(A000073(i), i=0..n+1) ; end: isA := proc(n) if n = 1 then RETURN(true) ; fi; if A008937(n-2) mod n = 0 then true; else false ; fi; end: for n from 1 to 2000 do if isA(n) then printf("%d, ", n) ; fi; od ;
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CROSSREFS
| Cf. A000073, A008937, A140973.
Sequence in context: A196197 A124690 A195877 * A107205 A139839 A118104
Adjacent sequences: A141576 A141577 A141578 * A141580 A141581 A141582
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KEYWORD
| nonn
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AUTHOR
| R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 19 2008
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