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A121388 Table read by antidiagonals which classifies the proper odd numbers by form (i,j) where i and j are the number of prime factors of the form 4k-1 and 4k+1 respectively. 2

%I #4 Mar 31 2012 13:23:38

%S 3,5,7,9,13,11,15,21,17,19,25,35,33,29,23,27,65,39,49,37,31,45,63,85,

%T 51,57,41,43,75,105,99,145,55,69,53,47,125,175,117,147,169,87,77,61,

%U 59,81,325,195,153,171,185,91,93,73,67,135,189,425,255,165,207,205,95,121,89

%N Table read by antidiagonals which classifies the proper odd numbers by form (i,j) where i and j are the number of prime factors of the form 4k-1 and 4k+1 respectively.

%e Table begins:

%e Row(i,j)

%e 1: (1,0) 3,7,11,19,23,31,43,47,59,67,71,79,83,103,... (A002145)

%e 2: (0,1) 5,13,17,29,37,41,53,61,73,89,97,101,109,... (A002144)

%e 3: (2,0) 9,21,33,49,57,69,77,93,121,129,133,141,... (A107978)

%e 4: (1,1) 15,35,39,51,55,87,91,95,111,115,119,... (A080774)

%e 5: (0,2) 25,65,85,145,169,185,205,221,265,289,... (A121387)

%e 6: (3,0) 27,63,99,147,171,207,231,279,343,...

%e 7: (2,1) 45,105,117,153,165,245,261,273,...

%e 8: (1,2) 75,175,195,255,275,435,455,...

%e 9: (0,3) 125,325,425,725,845,925,...

%e 10:(4,0) 81,189,297,441,513,...

%e 11:(3,1) 135,315,351,459,...

%e 12:(2,2) 225,525,585,...

%e 13:(1,3) 375,875,...

%e 14:(0,4) 625,...

%Y Cf. A120027. Subsequences begin A002145 A002144 A107978 A080774 A121387.

%K nonn,tabl

%O 1,1

%A _Alford Arnold_, Jul 26 2006

%E Edited, corrected and extended by _Ray Chandler_, Aug 08 2010

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Last modified March 29 10:22 EDT 2024. Contains 371268 sequences. (Running on oeis4.)