%I #6 Dec 18 2015 11:21:40
%S 0,1,2,3,4,5,6,7,7,8,9,9,10,11,11,11,12,13,13,13,14,15,15,15,15,16,17,
%T 17,17,17,18,19,19,19,19,19,20,21,21,21,21,21,22,23,23,23,23,23,23,24,
%U 25,25,25,25,25,25,26,27,27,27,27,27,27,27,28,29,29,29,29,29,29,29,30,31,31,31,31,31,31,31,31,32
%N Spiralwise distance to the nearest inner neighbor in Ulam-style square-spirals using zero-based indexing: a(0) = 0, for n >= 1, a(n) = n - A265409(n).
%H Antti Karttunen, <a href="/A265359/b265359.txt">Table of n, a(n) for n = 0..10000</a>
%F a(0) = 0, for n >= 1, a(n) = n - A265409(n).
%F If n <= 7, then a(n) = n, otherwise a(n) = a(n-1) + A240025(n) + A240025(n-1).
%o (Scheme, two variants)
%o (define (A265359 n) (if (zero? n) n (- n (A265409 n))))
%o (definec (A265359 n) (cond ((<= n 7) n) (else (+ (A265359 (- n 1)) (A240025 n) (A240025 (- n 1))))))
%Y Cf. A000267, A002620, A240025, A265409.
%K nonn
%O 0,3
%A _Antti Karttunen_, Dec 16 2015