%I #10 Dec 03 2023 07:06:40
%S 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,
%T 0,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,
%U 0,1,1,0,1,1,1,1,0,0,0,0,0,0
%N T(n,k) = [k is strongly prime to n], the indicator function of strong coprimality, triangle read by rows.
%C k is strongly prime to n iff k is relatively prime to n and k does not divide n-1.
%C T(n,k) = [k is strong prime to n] where [] denotes the Iverson bracket.
%H Peter Luschny, <a href="http://www.oeis.org/wiki/User:Peter_Luschny/StrongCoprimality">Strong coprimality</a>.
%e [n=0] 0
%e [n=1] 0, 0
%e [n=2] 0, 0, 0
%e [n=3] 0, 0, 0, 0
%e [n=4] 0, 0, 0, 0, 0
%e [n=5] 0, 0, 0, 1, 0, 0
%e Let n = 5 then the numbers prime to n are {1, 2, 3, 4} and the positive divisors of n-1 are {1, 2, 4}. Thus only 3 is strong prime to 5.
%o (SageMath)
%o def isstrongprimeto(k, n): return not(k.divides(n - 1)) and gcd(k, n) == 1
%o for n in srange(12): print([int(isstrongprimeto(k, n)) for k in srange(n+1)])
%o # _Peter Luschny_, Dec 03 2023
%Y Cf. A181830, A181831, A181832, A181838, A054431.
%K nonn,tabl
%O 0
%A _Peter Luschny_, Nov 17 2010
%E Corrected T(1, 1) to 0 by _Peter Luschny_, Dec 03 2023
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