A130419 - OEIS

%I #11 Jul 21 2024 10:55:44

%S 1,1,3,1,2,4,1,3,5,7,1,2,4,7,8,1,5,7,11,13,17,1,2,4,8,11,13,16,1,5,7,

%T 11,13,17,19,23,1,2,4,8,11,13,16,17,19,1,7,11,13,17,19,23,29,31,37,1,

%U 2,4,8,13,16,17,19,23,26,29,1,7,11,13,17,19,23,29,31,37,41,43,1,2,4,8,16,17

%N Triangle (of n terms per row) where t(n,m) = the m-th positive integer which is coprime to n!!. (n!! = n*(n-2)*(n-4)..*(2 or 1).).

%p A130419 := proc(n,m) local ndf,mprime,a ; ndf := doublefactorial(n) ; a := 0 ; for mprime from 1 to m do a := a+1 ; while gcd(a,ndf) <> 1 do a := a+1 ; od ; od ; RETURN(a) ; end: for n from 1 to 15 do for m from 1 to n do printf("%d, ",A130419(n,m)) ; od ; od ; # _R. J. Mathar_, Jun 06 2007

%t T[n_, m_] := Module[{ndf = n!!, mprime, a = 0}, For[mprime = 1, mprime <= m, mprime++, a++; While[GCD[a, ndf] != 1, a++]]; Return[a]];

%t Table[T[n, m], {n, 1, 15}, {m, 1, n}] // Flatten (* _Jean-François Alcover_, Jul 21 2024, after _R. J. Mathar_ *)

%Y Cf. A130420, A130418.

%K nonn,tabl

%O 1,3

%A _Leroy Quet_, May 25 2007

%E More terms from _R. J. Mathar_, Jun 06 2007