A324481 Index of first occurrence of n in the spiral shown in A274641.

0, 1, 2, 3, 7, 8, 26, 27, 30, 34, 35, 48, 55, 62, 63, 80, 101, 119, 130, 131, 155, 180, 210, 224, 253, 254, 271, 303, 305, 321, 322, 323, 419, 483, 504, 505, 568, 571, 573, 624, 649, 650, 728, 755, 810, 812, 840, 898, 953, 954, 956, 957, 959, 960, 1189

Offset

0,3

Comments

Also index of first occurrence of n+1 in the spiral shown in A274640.

Links

N. J. A. Sloane, Table of n, a(n) for n = 0..223

Formula

Conjecture: a(n) = c(n)*n^2 with 0.32 <= c(n) <= 1 for all n, maybe lim c(n) ~ 0.4. - M. F. Hasler, Feb 01 2025

Prog

(Python) A324481 = lambda n: next(i for i, a in enumerate(A274640()) if a==n+1) # slow
(Python)
def A324481(): # generator of the sequence
   n=1
   for i, a in enumerate(A274640()):
      if a==n: yield i; n += 1
[a for a, _ in zip(A324481(), range(99))] # M. F. Hasler, Feb 01 2025

Crossrefs

Cf. A274640, A274641.

Sequence in context: A369350 A206725 A129645 * A112994 A056036 A056432

Adjacent sequences: A324478 A324479 A324480 * A324482 A324483 A324484

Keyword

nonn

Author

N. J. A. Sloane, Mar 11 2019

Status

approved