A332850 Numbers k = a^2 + b^2 such that reversal(k) = a^2 - b^2 for a > b > 0, where reversal is A004086.

699796, 4854634, 6752626, 84036010, 931910661, 21584860960, 52554850525, 467170024564, 637843128736, 638730439636, 638734039636, 638943127636, 727830438745, 727834038745, 746710459825, 746754019825, 748943127625, 9894192267061, 401309596403104, 844181015028970

Offset: 1

Author

Metin Sariyar, Feb 26 2020

Keywords

• nonn
• base

Comments

When b=0, the palindromic numbers m = a^2 + b^2 such that reversal(m) = a^2 - b^2, are A002779 (palindromic squares).

a(19) > 3*10^14, if it exists. - Giovanni Resta, Feb 27 2020

Examples

			699796 = 836^2 + 30^2 and 697996 = 836^2 - 30^2.
		

Crossrefs

Cf. A002779, A004086, A035519, A055096, A202386.

Programs

Mathematica

Do[If[IntegerReverse[a^2+b^2]==a^2-b^2,Print[{a^2+b^2,a,b}]],{a,1,50000},{b,1,a-1}]

PARI

isok(k) = {my(r = fromdigits(Vecrev(digits(k))), s = r+k, d = k-r); d && !(s % 2) && issquare(s/2) && !(d % 2) && issquare(d/2); } \\ Michel Marcus, Feb 27 2020

Extensions

a(6)-a(18) from Giovanni Resta, Feb 27 2020

a(19)-a(20) from Jinyuan Wang, Apr 10 2025