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A119762
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Irregular array where row n is the distinct primes which divide the sum of all previous rows. a(1)=2.
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1
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2, 2, 2, 2, 3, 11, 2, 11, 5, 7, 47, 2, 47, 11, 13, 167, 2, 167, 503, 2, 503, 1511, 2, 1511, 5, 907, 13, 419, 5879, 2, 5879, 31, 569, 13, 23, 61, 2, 3, 191, 2, 41, 113, 2, 73, 29, 647, 7, 2777, 71, 313, 13, 37, 47, 2, 3, 11, 43, 13, 17, 103, 2, 3, 53, 2, 23, 499, 2, 3, 7, 13, 43, 2
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OFFSET
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1,1
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LINKS
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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,k)=A000040(s) for some s. - R. J. Mathar, Jun 23 2006
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EXAMPLE
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Array begins:
2
2
2
2,3
11
2,11
5,7
47
2,47
The sum of these terms is 143.
Since the distinct primes which divide 143 are 11 and 13, row 10 =(11,13).
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MAPLE
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A119762 := proc(nmax) local a, dvs, j; a := [2] ; while nops(a) < nmax do dvs := op(2, ifactors(sum('a[i]', i=1..nops(a)))) ; for j from 1 to nops(dvs) do a := [op(a), op(1, op(j, dvs))] ; od ; od ; end: a := A119762(200) : for i from 1 to nops(a) do printf("%d, ", a[i]) ; od ; # R. J. Mathar, Jun 23 2006
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PROG
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(PLT Scheme) ;; factorize is a prime-factorization routine that returns a list of (prime exponent) pairs for each factor.
(cond
[(= n 0) seq]
[else (A119762 (sub1 n) (append seq (map first (factorize (apply + seq)))))]))
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CROSSREFS
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KEYWORD
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nonn,tabf
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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