login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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. 2
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 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,39

COMMENTS

Row products give A139554.

LINKS

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

EXAMPLE

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

PROG

(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

CROSSREFS

Cf. A139554, A139547, A003418.

Sequence in context: A170977 A039737 A144382 * A078379 A121657 A043282

Adjacent sequences:  A139550 A139551 A139552 * A139554 A139555 A139556

KEYWORD

nonn,tabl

AUTHOR

Mats Granvik, Apr 27 2008

EXTENSIONS

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

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 20 12:21 EDT 2021. Contains 348106 sequences. (Running on oeis4.)