OFFSET
3,2
COMMENTS
LINKS
Michael De Vlieger, Table of n, a(n) for n = 3..11028 (rows 3 <= n <= 150).
EXAMPLE
============================================================
. n \ k | 2 3 4 5 6 7 8 9 10 11 12 13 14
--------|---------------------------------------------------
. 3 | 0
. 4 | 2 0
. 5 | 0 0 0
. 6 | 2 3 2 0
. 7 | 0 0 0 0 0
. 8 | 2 0 2 0 2 0
. 9 | 0 3 0 0 3 0 0
. 10 | 2 0 2 5 2 0 2 0
. 11 | 0 0 0 0 0 0 0 0 0
. 12 | 2 3 2 0 2 0 2 3 2 0
. 13 | 0 0 0 0 0 0 0 0 0 0 0
. 14 | 2 0 2 0 2 7 2 0 2 0 2 0
. 15 | 0 3 0 5 3 0 0 3 5 0 3 0 0
MATHEMATICA
Table[If[CoprimeQ[n, k], 0, First@ Intersection[FactorInteger[n][[All, 1]], FactorInteger[k][[All, 1]] ]], {n, 3, 15}, {k, 2, n - 1}] // Flatten (* Michael De Vlieger, Jan 23 2018 *)
PROG
(PARI) t(n, k) = if(gcd(n, k) > 1, my(f=factor(n)[, 1]~, g=factor(k)[, 1]~); return(vecmin(setintersect(f, g)))); 0
trianglerows(n) = for(x=3, n+2, for(y=2, x-1, print1(t(x, y), ", ")); print(""))
trianglerows(13) \\ print upper 13 rows of triangle
CROSSREFS
KEYWORD
AUTHOR
Felix Fröhlich, Jan 09 2018
EXTENSIONS
Value of T(12, 6) and PARI program corrected by Felix Fröhlich, Jan 23 2018
STATUS
approved