A156297 Triangle T(n,k) read by rows. If n = k^2 then 1 else 0.

1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 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, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset

1,1

Comments

Triangle can be used as an operator.

Links

Antti Karttunen, Table of n, a(n) for n = 1..97461; the first 441 (21^2) rows of triangle

Index entries for characteristic functions

Example

Table begins:
1;
0,0;
0,0,0;
0,1,0,0;
0,0,0,0,0;
0,0,0,0,0,0;
0,0,0,0,0,0,0;
0,0,0,0,0,0,0,0;
0,0,1,0,0,0,0,0,0;
0,0,0,0,0,0,0,0,0,0;
0,0,0,0,0,0,0,0,0,0,0;
0,0,0,0,0,0,0,0,0,0,0,0;
0,0,0,0,0,0,0,0,0,0,0,0,0;
0,0,0,0,0,0,0,0,0,0,0,0,0,0;
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;

Prog

(PARI)
up_to = 97461; \\ binomial(441+1, 2), 441 = 21^2
A156297tr(n, k) = ((k*k) == n);
A156297list(up_to) = { my(v = vector(up_to), i=0); for(n=1, oo, for(k=1, n, i++; if(i > up_to, return(v)); v[i] = A156297tr(n, k))); (v); };
v156297 = A156297list(up_to);
A156297(n) = v156297[n]; \\ Antti Karttunen, Dec 24 2018

Crossrefs

Sequence in context: A354037 A185118 A240332 * A015626 A015920 A014744

Adjacent sequences: A156294 A156295 A156296 * A156298 A156299 A156300

Keyword

nonn,tabl

Author

Mats Granvik, Feb 07 2009

Status

approved