A289140 Positive numbers k such that rev(k)^2 + rev(k^2) is a square, where rev(n) = A004086(n) is the digital reverse of n.

998586, 3632658, 9985860, 36326580, 74471091, 99664458, 99858600, 363265800, 634826115, 743193501, 744710910, 756335085, 759317343, 996644580, 998586000, 3632658000, 6348261150, 7177621788, 7431935010, 7447109100, 7563350850, 7593173430, 9966445800

Offset: 1

Author

Giovanni Resta, Jun 26 2017

Keywords

• nonn
• base

Comments

Every term must be a multiple of 3.

Examples

			998586 is a term since rev(998586^2) + 685899^2 = 1079100^2.
		

Crossrefs

Cf. A004086, A061230, A061231, A068536, A102859, A113798, A202386, A256515.

Programs

Mathematica

rev[n_] := FromDigits@ Reverse@ IntegerDigits@ n; Parallelize@ Select[3 Range[4 10^6], IntegerQ@ Sqrt[rev[#^2] + rev[#]^2] &]

PARI

isok(n) = issquare(fromdigits(Vecrev(digits(n)))^2 + fromdigits(Vecrev(digits(n^2)))); \\ Michel Marcus, Jun 29 2017