A273358 Numbers n such that the decimal number concat(3,n) is a square.

6, 24, 61, 136, 249, 364, 481, 600, 721, 844, 969, 1329, 1684, 2041, 2400, 2761, 3124, 3489, 3856, 4225, 4596, 4969, 5344, 5721, 6100, 6481, 6864, 7249, 7636, 8025, 8416, 8809, 9204, 9601, 10249, 11364, 12481, 13600, 14721, 15844, 16969, 18096

Offset

1,1

Comments

Elements are squares of integers in (sqrt(31), sqrt(40)) * sqrt(10)^k without the leading 3 elements for nonnegative k. - David A. Corneth, May 20 2016

Links

Nathan Fox, Table of n, a(n) for n = 1..11067

Example

61 is a member because 361 = 19^2 is a square.
0 is not a member because 30 is not a square.

Maple

t1:=[];
for k from 1 to 20000 do
if issqr(k+3*10^length(k)) then t1:=[op(t1), k]; fi;
od;
t1;

Prog

(Magma) [n: n in [1..20000 ] | IsSquare(Seqint(Intseq(n) cat Intseq(3)))]; // Marius A. Burtea, Mar 21 2019

Crossrefs

Cf. A272671, A273357, A273359, A273360, A273361, A273362, A273363, A273364.

Sequence in context: A371019 A370985 A101854 * A325517 A344508 A101877

Adjacent sequences: A273355 A273356 A273357 * A273359 A273360 A273361

Keyword

nonn,base

Author

Nathan Fox, Brooke Logan, and N. J. A. Sloane, May 20 2016

Status

approved