A319483 a(n) = A128921(n)^2.

0, 1, 4, 9, 121, 484, 1089, 9801, 10201, 12321, 14641, 40804, 44944, 1002001, 1234321, 4008004, 100020001, 102030201, 104060401, 121242121, 123454321, 125686521, 400080004, 404090404, 10000200001, 10221412201, 12102420121, 12345654321, 40000800004, 1000002000001

Offset

1,3

Links

Table of n, a(n) for n=1..30.

Example

b(n) = reverse of a(n).
n | A128921(n) |   a(n) |   b(n) | Root of b(n) |
--+------------+--------+--------+--------------+
1 |         0  |     0  |     0  |           0  |
2 |         1  |     1  |     1  |           1  |
3 |         2  |     4  |     4  |           2  |
4 |         3  |     9  |     9  |           3  |
5 |        11  |   121  |   121  |          11  |
6 |        22  |   484  |   484  |          22  |
7 |        33  |  1089  |  9801  |          99  |
8 |        99  |  9801  |  1089  |          33  |
9 |       101  | 10201  | 10201  |         101  |

Prog

(Python)
from itertools import count, chain, islice
from sympy.ntheory.primetest import is_square
def A319483_gen(): # generator of terms
    return filter(lambda n:is_square(int(str(n)[::-1])), map(lambda n: n**2, chain((0, ), chain.from_iterable(chain((int((s:=str(d))+s[-2::-1]) for d in range(10**l, 10**(l+1))), (int((s:=str(d))+s[::-1]) for d in range(10**l, 10**(l+1)))) for l in count(0)))))
A319483_list = list(islice(A319483_gen(), 20)) # Chai Wah Wu, Jun 23 2022

Crossrefs

Cf. A002113, A128921, A319482.

Sequence in context: A131760 A002779 A028817 * A057136 A048411 A225739

Adjacent sequences: A319480 A319481 A319482 * A319484 A319485 A319486

Keyword

nonn,base

Author

Seiichi Manyama, Sep 20 2018

Status

approved