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Search: id:A136195
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| A136195 |
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Irregular array read by rows: row n contains the sums of each pair of consecutive positive divisors of n. |
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2
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| 3, 4, 3, 6, 6, 3, 5, 9, 8, 3, 6, 12, 4, 12, 3, 7, 15, 12, 3, 5, 7, 10, 18, 14, 3, 9, 21, 4, 8, 20, 3, 6, 12, 24, 18, 3, 5, 9, 15, 27, 20, 3, 6, 9, 15, 30, 4, 10, 28, 3, 13, 33, 24, 3, 5, 7, 10, 14, 20, 36, 6, 30, 3, 15, 39, 4, 12, 36, 3, 6, 11, 21, 42, 30, 3, 5, 8, 11, 16, 25, 45
(list; graph; listen)
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OFFSET
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2,1
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COMMENT
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The first listed row is row 2. Row n contains d(n)-1 terms, where d(n) is the number of positive divisors of n.
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EXAMPLE
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The positive divisors of 20 are 1,2,4,5,10,20. 1+2=3. 2+4=6. 4+5=9. 5+10=15. 10+20=30. So row 20 is (3,6,9,15,30).
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MAPLE
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with(numtheory): a:=proc(n) local dn: dn:=divisors(n): seq(dn[i]+dn[i+1], i= 1..nops(dn)-1) end proc: for n from 2 to 30 do a(n) end do; - Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 05 2008
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CROSSREFS
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Cf. A136193.
Adjacent sequences: A136192 A136193 A136194 this_sequence A136196 A136197 A136198
Sequence in context: A097857 A110738 A005092 this_sequence A117892 A074372 A049276
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KEYWORD
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nonn,tabf
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Dec 20 2007
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 05 2008
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