A249972 Numbers whose squares remain squares when prepended with 6 and appended with 25 in base 10.

4719393690, 11807874630, 27742949118597124246940412263153220, 3115332518157379156757021966320555019484, 260714191448671809506865610677483779874998640, 7585133892508411962174194534029951072870678740

Offset

1,1

Comments

No other terms below 10^121. - Max Alekseyev, Nov 07 2024

Links

Table of n, a(n) for n=1..6.

Example

4719393690^2 = 22272676801211816100, 62227267680121181610025 = 249453938995^2.

Prog

(PARI) isok(n) = issquare(eval(concat([6, Str(n^2), 25]))) \\ Michel Marcus, Jul 20 2017

Crossrefs

Cf. A249621, A249968, A249969, A249970, A249971, A250433, A250434, A250435.

Sequence in context: A124977 A128172 A050259 * A233494 A175568 A224472

Adjacent sequences: A249969 A249970 A249971 * A249973 A249974 A249975

Keyword

nonn,base

Author

Chai Wah Wu, Nov 22 2014

Extensions

a(5) from Chai Wah Wu, Jul 19 2017

a(6) from Max Alekseyev, Oct 31 2024

Status

approved