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

1,1

Comments

Every term must be a multiple of 3.

Links

Table of n, a(n) for n=1..23.

Example

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

Mathematica

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

Prog

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

Crossrefs

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

Sequence in context: A341551 A216276 A252903 * A033426 A277400 A017178

Adjacent sequences: A289137 A289138 A289139 * A289141 A289142 A289143

Keyword

nonn,base

Author

Giovanni Resta, Jun 26 2017

Status

approved