A139553 Triangle read by rows: T(n,k) = if n>=4*k and n<4*k*A014963(k) then k else 1; T(n,0)=1.

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1

Offset: 0

Author

Mats Granvik, Apr 27 2008

Keywords

• nonn
• tabl

Comments

Row products give A139554.

Examples

			Row products of the triangle are:
1 = 1
1*1 = 1
1*1*1 = 1
1*1*1*1 = 1
1*1*1*1*1 = 1
1*1*1*1*1*1 = 1
1*1*1*1*1*1*1 = 1
1*1*1*1*1*1*1*1 = 1
1*1*2*1*1*1*1*1*1 = 2
		

Links

• Antti Karttunen, Table of n, a(n) for n = 0..23219; the first 215 rows of triangle

Crossrefs

Cf. A139554, A139547, A003418.

Programs

Excel

=if(and(row()-1>=(column()-1)*4;row()-1 < A014963(k-1)*(column()-1)*4);column()-1;1)

PARI

up_to = 23220; \\ binomial(215+1,2)
A014963(n) = { ispower(n, , &n); if(isprime(n), n, 1); }; \\ From A014963 by Charles R Greathouse IV, Jun 10 2011
A139553tr(n, k) = if(0==k,1,if((n>=(4*k))&&(n<(4*k*A014963(k))),k,1));
A139553list(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] = A139553tr(n-1,k-1))); (v); };
v139553 = A139553list(up_to);
A139553(n) = v139553[1+n]; \\ Antti Karttunen, Jan 03 2019

Extensions

Typo in the definition corrected by Antti Karttunen, Jan 03 2019