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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A334741 Fill an infinite square array by following a spiral around the origin; in the central cell enter a(0)=1; thereafter, in the n-th cell, enter the sum of the entries of those earlier cells that are in the same row or column as that cell. 3
 1, 1, 1, 2, 3, 5, 8, 11, 21, 40, 47, 93, 180, 203, 397, 796, 1576, 1675, 3305, 6636, 13192, 14004, 27607, 55029, 110192, 220024, 226740, 450123, 898661, 1798700, 3594248, 3704800, 7354303, 14681369, 29349536, 58710640, 117394896, 119196748, 237492079 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS The spiral track being used here is the same as in A274640, except that the starting cell here is indexed 0 (as in A274641). The central cell gets index 0 (and we fill it in with the value a(0)=1). LINKS Peter Kagey, Table of n, a(n) for n = 0..2499 EXAMPLE Spiral begins:      3----2----1      |         |      5    1----1   47      |              |      8---11---21---40 a(11) = 47 = 1 + 1 + 5 + 40, the sum of the cells in its row and column. PROG (PARI) \\ here P(n) returns A174344 and A274923 as pair. P(n)={my(m=sqrtint(n), k=ceil(m/2)); n -= 4*k^2; if(n<0, if(n<-m, [k, 3*k+n], [-k-n, k]), if(n

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.

Last modified June 21 04:10 EDT 2021. Contains 345354 sequences. (Running on oeis4.)