A265359 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).

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, 17, 17, 17, 18, 19, 19, 19, 19, 19, 20, 21, 21, 21, 21, 21, 22, 23, 23, 23, 23, 23, 23, 24, 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

Offset

0,3

Links

Antti Karttunen, Table of n, a(n) for n = 0..10000

Formula

a(0) = 0, for n >= 1, a(n) = n - A265409(n).

If n <= 7, then a(n) = n, otherwise a(n) = a(n-1) + A240025(n) + A240025(n-1).

Prog

(Scheme, two variants)
(define (A265359 n) (if (zero? n) n (- n (A265409 n))))
(definec (A265359 n) (cond ((<= n 7) n) (else (+ (A265359 (- n 1)) (A240025 n) (A240025 (- n 1))))))

Crossrefs

Cf. A000267, A002620, A240025, A265409.

Sequence in context: A134679 A100721 A337979 * A271490 A252649 A095703

Adjacent sequences: A265356 A265357 A265358 * A265360 A265361 A265362

Keyword

nonn

Author

Antti Karttunen, Dec 16 2015

Status

approved