A159923 - OEIS

A159923

Rectangular array read by antidiagonals: a(m,n) = greatest noncomposite (1 or prime) that divides both m and n.

1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 3, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 3, 1, 1, 3, 1, 1, 1, 2, 1, 2, 5, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 2, 1, 3, 1, 2, 3, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 7, 2, 1, 2, 1, 2, 1, 1, 1, 3, 1, 5, 3, 1, 1, 3, 5, 1, 3, 1, 1

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OFFSET

1,5

COMMENTS

The array is symmetric along the diagonal, so there is a triangular version with the same amount of information that reads the array along rows up to the diagonal: 1,1,2,1,1,3,1,2,1,2,1,1,1,1,5,1,... - R. J. Mathar, Apr 29 2009

LINKS

Table of n, a(n) for n=1..105.

MAPLE

A159923 := proc(n, m) local g; for g from max(n, m) to 2 by -1 do if isprime(g) and (n mod g) = 0 and (m mod g) = 0 then RETURN(g) ; fi; od: RETURN(1) ; end: for d from 2 to 22 do for m from 1 to d-1 do n := d-m ; printf("%d, ", A159923(n, m)) ; od: od: # R. J. Mathar, Apr 29 2009

CROSSREFS

Sequence in context: A140194 A353282 A350714 * A287957 A003989 A091255

Adjacent sequences: A159920 A159921 A159922 * A159924 A159925 A159926

KEYWORD

nonn,tabl

AUTHOR

Leroy Quet, Apr 26 2009

EXTENSIONS

More terms from R. J. Mathar, Apr 29 2009

STATUS

approved