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 A181837 T(n,k) = [k is strongly prime to n], the indicator function of strong coprimality, triangle read by rows. 1
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 OFFSET 0 COMMENTS k is strongly prime to n iff k is relatively prime to n and k does not divide n-1. T(n,k) = [k is strong prime to n] where [] denotes the Iverson bracket. LINKS Peter Luschny, Strong coprimality. EXAMPLE [n=0]          0 [n=1]         0, 1 [n=2]       0, 0, 0 [n=3]      0, 0, 0, 0 [n=4]    0, 0, 0, 0, 0 [n=5]   0, 0, 0, 1, 0, 0 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. MAPLE A181837_triangle := proc(M) local strongCoprimes, triangle; strongCoprimes := n -> select(k->igcd(k, n)=1, {\$1..n}) minus numtheory[divisors](n-1): triangle := proc(N, C) local T, L, k, n; for n from 0 to N do   T := C(n); L := NULL;   for k from 0 to n do     L := L, `if`(member(k, T), 1, 0)   od;   print(L) od end: triangle(M, strongCoprimes) end: CROSSREFS Cf. A181830, A181831, A181832, A181838, A054431. Sequence in context: A191153 A214210 A204547 * A185706 A288167 A288991 Adjacent sequences:  A181834 A181835 A181836 * A181838 A181839 A181840 KEYWORD nonn,tabl AUTHOR Peter Luschny, Nov 17 2010 STATUS approved

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