A131504 - OEIS

%I #10 Aug 26 2015 00:38:37

%S 1,1,3,1,3,4,1,5,7,7,1,3,4,7,6,1,3,7,11,11,17,1,5,4,7,8,17,8,1,3,7,9,

%T 11,17,15,15,1,3,4,11,6,17,11,15,13,1,5,7,9,17,19,15,23,25,23,1,3,4,7,

%U 6,17,9,15,13,23,12,1,3,11,11,11,19,23,19,25,37,23,35,1,5,4,9,8,17,8,23,16

%N Array read by antidiagonals: a(m,n) = m-th integer from among those positive integers that are coprime to (m*n).

%e For example:

%e a(6,5) = 19 because the positive integers which are coprime to (5*6) are 1,7,11,13,17,19,23,29,... and the 6th of these is 19.

%e Array begins:

%e 1, 3, 4, 7, 6,17, 8,15,13,23,12,35,14,...

%e 1, 3, 7, 7,11,17,15,15,25,23,23,35,27,...

%e 1, 5, 4,11, 8,17,11,23,13,37,17,35,20,...

%e 1, 3, 7, 7,11,17,15,15,25,23,23,35,27,...

%e 1, 3, 4, 9, 6,19, 9,19,16,23,14,43,17,...

%e 1, 5, 7,11,17,17,23,23,25,37,35,35,41,...

%e 1, 3, 4, 9, 6,19, 8,17,16,29,13,41,16,...

%e 1, 3, 7, 7,11,17,15,15,25,23,23,35,27,...

%e 1, 5, 4,11, 8,17,11,23,13,37,17,35,20,...

%e 1, 3,11, 9,11,19,19,19,31,23,29,43,33,...

%e 1, 3, 4, 7, 6,19, 8,17,14,27,12,37,15,...

%e 1, 5, 7,11,17,17,23,23,25,37,35,35,41,...

%p A131504 := proc(n,m) local mn,a,k ; mn := m*n ; k := 1; for a from 1 do if gcd(a,mn) = 1 then if k = m then RETURN(a) ; fi ; k := k+1 ; fi ; od: end: for d from 1 to 14 do for m from 1 to d do printf("%d,",A131504(d+1-m,m)) ; od: od: # _R. J. Mathar_, Oct 26 2007

%Y Cf. A069213.

%K nonn,tabl

%O 1,3

%A _Leroy Quet_, Aug 13 2007

%E More terms from _R. J. Mathar_, Oct 26 2007