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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.
0
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.
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
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Jun 26 2017
STATUS
approved