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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
0, 0, 1, 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, 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, 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0 (list; table; graph; refs; listen; history; text; internal format)
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

Table of n, a(n) for n=0..81.

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 A188371 A188472

Adjacent sequences:  A181834 A181835 A181836 * A181838 A181839 A181840

KEYWORD

nonn,tabl

AUTHOR

Peter Luschny, Nov 17 2010

STATUS

approved

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Last modified November 21 14:12 EST 2014. Contains 249779 sequences.