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A332850 Numbers k = a^2 + b^2 such that reversal(k) = a^2 - b^2 for a > b > 0, where reversal is A004086. 0
699796, 4854634, 6752626, 84036010, 931910661, 21584860960, 52554850525, 467170024564, 637843128736, 638730439636, 638734039636, 638943127636, 727830438745, 727834038745, 746710459825, 746754019825, 748943127625, 9894192267061 (list; graph; refs; listen; history; text; internal format)
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 * A183835 A273969 A203834

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

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Last modified September 22 20:23 EDT 2020. Contains 337291 sequences. (Running on oeis4.)