

A308055


a(1)=2; for n > 1, a(n) is the square root of the smallest square with a(n1) as a prefix in base 10.


3



2, 5, 23, 48, 22, 15, 39, 63, 251, 501, 224, 474, 689, 2625, 5124, 22637, 47579, 68978, 83053, 28819, 53684, 2317, 4814, 6939, 26342, 51325, 71642, 84642, 290933, 1705676, 4129984, 20322363, 45080332, 67141889, 25911752, 16097128, 12687446, 35619442, 59682026
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OFFSET

1,1


COMMENTS

The sequence contains the following squares: 315844, 289, 81, 9, and is eventually periodic.  Rémy Sigrist, Jul 13 2019


LINKS

Rémy Sigrist, Table of n, a(n) for n = 1..100
Rémy Sigrist, PARI program for A308055


FORMULA

From Rémy Sigrist, Jul 13 2019: (Begin)
a(n+1) = A018851(a(n)).
a(n + 4) = a(n) for n >= 83.
(End)


EXAMPLE

a(1) = 2;
25 is the smallest square with 2 as a prefix;
a(2) = sqrt(25) = 5;
529 is the smallest square with 5 as a prefix;
a(3) = sqrt(529) = 23;
2304 is the smallest square with 23 as a prefix;
a(4) = sqrt(2304) = 48; etc.


PROG

(PARI) See Links section.


CROSSREFS

Cf. A000290 (squares), A018851.
Sequence in context: A175444 A233443 A156314 * A173396 A023186 A023188
Adjacent sequences: A308052 A308053 A308054 * A308056 A308057 A308058


KEYWORD

nonn,base,easy,look


AUTHOR

Sean Lipton, May 09 2019


EXTENSIONS

a(31)a(39) from Jon E. Schoenfield, May 10 2019
Comments corrected by Rémy Sigrist, Jul 13 2019


STATUS

approved



