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

Offset

1,1

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

Links

Table of n, a(n) for n=1..18.

Example

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

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}]

Prog

(PARI) isok(k) = {my(r = fromdigits(Vecrev(digits(k))), s = r+k, d = r-k); if (d && !(s % 2) && issquare(s/2) && !(d % 2) && issquare(d/2), 1, 0); } \\ Michel Marcus, Feb 27 2020

Crossrefs

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

Sequence in context: A027829 A258129 A204496 * A378475 A183835 A273969

Adjacent sequences: A332847 A332848 A332849 * A332851 A332852 A332853

Keyword

nonn,base,more

Author

Metin Sariyar, Feb 26 2020

Extensions

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

Status

approved