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 A027749 Take the list 1,2,3,4,... and replace each n with all d > 1 that divide n. 4
 1, 2, 3, 2, 4, 5, 2, 3, 6, 7, 2, 4, 8, 3, 9, 2, 5, 10, 11, 2, 3, 4, 6, 12, 13, 2, 7, 14, 3, 5, 15, 2, 4, 8, 16, 17, 2, 3, 6, 9, 18, 19, 2, 4, 5, 10, 20, 3, 7, 21, 2, 11, 22, 23, 2, 3, 4, 6, 8, 12, 24, 5, 25, 2, 13, 26, 3, 9, 27, 2, 4, 7, 14, 28, 29, 2, 3, 5, 6, 10, 15, 30, 31, 2, 4, 8, 16, 32, 3, 11, 33, 2, 17, 34, 5, 7, 35 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(A002541(n)+1)=n; a(A002541(n)+2)=A020639(n+1). - Reinhard Zumkeller, Nov 22 2003 Seen as a triangle read by rows: T(1,1)=1 and T(n,k)=A027750(n,k+1) for n>1, 1<=k

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