

A081485


Triangle read by rows in which the nth row contains the smallest set of n coprime numbers with a sum which is a multiple of n.


4



1, 1, 3, 1, 2, 3, 1, 3, 5, 7, 1, 2, 3, 5, 19, 1, 3, 5, 7, 13, 19, 1, 2, 3, 5, 7, 11, 13, 1, 3, 5, 7, 11, 13, 17, 23, 1, 2, 3, 5, 7, 11, 13, 17, 31, 1, 3, 5, 7, 11, 13, 17, 19, 23, 31, 1, 2, 3, 5, 7, 11, 13, 17, 19, 23, 31, 1, 3, 5, 7, 11, 13, 17, 19, 23, 29, 41, 47, 1, 2, 3, 5, 7, 11, 13, 17
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OFFSET

1,3


COMMENTS

In the row for 6 the fifth term is 13 and not 11 as this forces the sixth term divisible by (not coprime to 3) 3. For even n all the terms have to be odd. This sequence set should exhibit some interesting properties and needs attention.


LINKS

Franklin T. AdamsWatters, Rows n=1..80 of triangle, flattened


EXAMPLE

Triangle begins
1
1 3
1 2 3
1 3 5 7
1 2 3 5 19
1 3 5 7 13 19


PROG

Contribution from Franklin T. AdamsWatters, Apr 09 2009: (Start)
(PARI) arow(n) = {local(v, t, p, r);
if(n<=3, return(if(n==2, [1, 3], if(n==3, [1, 2, 3], [1]))));
v=vector(n); v[1]=1; v[2]=if(n%2==0, 3, 2); t=v[2]+1;
for(i=3, n2, v[i]=nextprime(v[i1]+1); t+=v[i]);
p=nextprime(v[n2]+1);
while(gcd(t+p, n)>1, p=nextprime(p+1));
v[n1]=p; t+=p; r=p\n*nt%n;
while(r<=p, r+=n);
while(!isprime(r), r+=n);
v[n]=r; v} (End)


CROSSREFS

Cf. A081486, A081487, A081488.
Sequence in context: A080511 A132399 A287616 * A100337 A036584 A260453
Adjacent sequences: A081482 A081483 A081484 * A081486 A081487 A081488


KEYWORD

nonn,tabl


AUTHOR

Amarnath Murthy, Mar 24 2003


EXTENSIONS

Corrected and extended by David Wasserman, Jun 03 2004


STATUS

approved



