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A232422 Integers n such that n^2 becomes another square under the map 8<=>9 (acting on the decimal digits). 0
621, 629, 6210, 6290, 43415, 44665, 62100, 62900, 113405, 113845, 434150, 446650, 621000, 629000, 677131, 677869, 918545, 971455, 1134050, 1138450, 1260718, 1264282, 1355425, 1391825, 3373885, 3375365, 3854525, 3867475, 4341500, 4466500, 6210000, 6290000, 6771310, 6778690, 9185450, 9714550 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If n is a term then 10n is also a term.

n^2 must contain an 8, a 9, or both. - Harvey P. Dale, Jun 17 2022

LINKS

Table of n, a(n) for n=1..36.

EXAMPLE

621^2=385641 <=> 395641 = 629^2, so both 621 and 629 are terms.

43415=1884862225 <=>1994962225=44665^2, so both 43415 and 44665 are terms.

MATHEMATICA

fQ[n_]:=Block[{id=IntegerDigits@n^2}, (MemberQ[id, 8]||MemberQ[id, 9])&&

IntegerQ[Sqrt[FromDigits[id/.{8->9, 9->8}]]]]; Reap[Do[If[fQ[n], Sow[n]], {n, 10000000}]][[2, 1]]

Select[Range[10^7], Max[IntegerDigits[#^2]]>7&&IntegerQ[Sqrt[ FromDigits[ IntegerDigits[ #^2]/.{8->9, 9->8}]]]&] (* Harvey P. Dale, Jun 17 2022 *)

CROSSREFS

A175789 (primes with similar property).

Sequence in context: A202239 A010031 A252527 * A335767 A189119 A203086

Adjacent sequences: A232419 A232420 A232421 * A232423 A232424 A232425

KEYWORD

nonn,base

AUTHOR

Zak Seidov, Nov 23 2013

STATUS

approved

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Last modified December 1 21:09 EST 2022. Contains 358484 sequences. (Running on oeis4.)