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A249971 Numbers whose squares remain squares when prepended with 5 and appended with 25 in base 10. 5

%I #8 Nov 22 2014 00:07:12

%S 16,30730,3727084,3127636818781854350,7536101752216453484,

%T 52452254824270668843034,260517421591511559294554416,

%U 20815875053039440273965644350185324640

%N Numbers whose squares remain squares when prepended with 5 and appended with 25 in base 10.

%e 30730^2 = 944332900, 594433290025 = 770995^2.

%o (PARI) isok(n) = issquare(eval(concat(5, concat(Str(n^2), 25)))); \\ _Michel Marcus_, Nov 20 2014

%Y Cf. A249968, A249969, A249970.

%K nonn,base

%O 1,1

%A _Chai Wah Wu_, Nov 19 2014

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Last modified July 13 09:13 EDT 2024. Contains 374274 sequences. (Running on oeis4.)