A053889 Squares composed of digits {1,2,9}.

1, 9, 121, 29929, 9991921, 1212919929, 1929229929, 1991212129, 2929299129, 1229129212921, 92222199291121, 219992999929921, 99221129991291219129, 2291192212129911919221121, 9992221299191112291912929211222129, 211192199129121999192121999211919121, 21112999921929291129929211912291229929191119991929921

Offset

1,2

Links

Table of n, a(n) for n=1..17.

Patrick De Geest, Squares containing at most three distinct digits, Index entries for related sequences.

Hisanori Mishima, Squares consisting of 3 different digits.

Author?, Source(txt)

Formula

a(n) = A053888(n)^2. - Elmo R. Oliveira, Jul 18 2025

Mathematica

Flatten[Table[Select[FromDigits/@Tuples[{1, 2, 9}, n], IntegerQ[Sqrt[#]]&], {n, 12}]] (* This program generates only the first 9 terms of the sequence *) (* Harvey P. Dale, Oct 19 2011 *)

Crossrefs

Cf. A053888.

Sequence in context: A045976 A276256 A276095 * A295372 A293284 A087584

Adjacent sequences: A053886 A053887 A053888 * A053890 A053891 A053892

Keyword

nonn,base

Author

Patrick De Geest, Mar 15 2000

Extensions

a(13) from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 04 2005

a(14) from Jon E. Schoenfield, Sep 03 2006

a(15)-a(16) from Mishima's webpage added by Max Alekseyev, Jun 17 2011

a(17) from Zhao Hui Du, Feb 29 2024

Status

approved