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Search: id:A119763
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| A119763 |
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Irregular array where row n is the positive integers which divide the sum of all previous rows. a(1)=1. |
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+0
1
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| 1, 1, 1, 2, 1, 5, 1, 11, 1, 23, 1, 47, 1, 5, 19, 95, 1, 5, 43, 215, 1, 479, 1, 7, 137, 959, 1, 2063, 1, 4127, 1, 5, 13, 65, 127, 635, 1651, 8255, 1, 83, 229, 19007, 1, 38327, 1, 5, 15331, 76655, 1, 137, 1231, 168647, 1, 13, 109, 239, 1417, 3107, 26051, 338663, 1, 19
(list; graph; listen)
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OFFSET
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1,4
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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FORMULA
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a(n,k) | sum(j=1..n-1,l=1,2,...) a(j,l). a(n,k) > a(n,k-1). a(n,1)=1. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 23 2006
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EXAMPLE
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Array begins:
1
1
1,2
1,5
1,11
1,23
1,47
1,5,19,95
The sum of these terms is 215.
Since the divisors 215 are 1,5,43 and 215, row 9 =(1,5,43,215).
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MAPLE
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A119763 := proc(nmax) local a, dvs; a := [1] ; while nops(a) < nmax do dvs := numtheory[divisors](sum('a[i]', i=1..nops(a))) ; a := [op(a), op(dvs) ] ; od ; end: a := A119763(200) ; for i from 1 to nops(a) do printf("%d, ", a[i]) ; od ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 23 2006
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PROGRAM
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; ; PLT DrScheme - Joshua Zucker (joshua.zucker(AT)stanfordalumni.org), Jun 21 2006
; ; positive-divisors gives the list of divisors of n in decreasing order
(define (A119763 n seq)
(cond
[(= n 0) seq]
[else (A119763 (sub1 n) (append seq (reverse (positive-divisors (apply + seq)))))]))
(A119763 20 (list 1))
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CROSSREFS
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Cf. A027750.
Sequence in context: A132081 A054251 A163963 this_sequence A092142 A140879 A006556
Adjacent sequences: A119760 A119761 A119762 this_sequence A119764 A119765 A119766
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KEYWORD
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nonn,tabf
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AUTHOR
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Leroy Quet Jun 18 2006
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EXTENSIONS
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More terms from Joshua Zucker (joshua.zucker(AT)stanfordalumni.org) and R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 21 2006
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