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%I #27 Dec 25 2016 23:16:18
%S 1,1,2,4,7,13,23,42,76,146,239,441,852,1389,2536,4971,9832,15312,
%T 27964,54801,108787,169086,308758,603612,1201837,2397202,3656904,
%U 6687912,13067709,25998877,51918269,79176868,144799285,282915788,562653823,1124083053,2246758839
%N 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 can be seen from that cell.
%C The spiral track being used here is the same as in A274640, except that the starting cell here is indexed 0 (as in A274641).
%C The central cell gets index 0 (and we fill it in with the value a(0)=1).
%C "Can be seen from" means "that are on the same row, column, diagonal, or antidiagonal as".
%H Lars Blomberg, <a href="/A280027/b280027.txt">Table of n, a(n) for n = 0..3384</a>
%e The central portion of the spiral is:
%e .
%e 7----4----2
%e | |
%e 13 1----1 239
%e | |
%e 23---42---76--146
%e .
%e After the terms a(0) to a(8) of the spiral have been filled in, the next cell contains 76+42+23+1+4 = 146 = a(9).
%Y Cf. A274640, A274641, A278180.
%K nonn,tabl
%O 0,3
%A _N. J. A. Sloane_, Dec 24 2016
%E More terms from _Lars Blomberg_, Dec 25 2016
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