A282455 Repdigit numbers that are the sum of two nonzero squares.

2, 5, 8, 333, 666

Offset

1,1

Comments

This sequence is complete - there are no other terms.

Links

Table of n, a(n) for n=1..5.

Wikipedia, Sum of two squares theorem

Index entries for sequences related to sums of squares

Formula

A000404 INTERSECT A010785.

Example

666 = 15^2 + 21^2, therefore 666 is a term.

Prog

(Magma) lst:=[]; for e in [1..3] do a:=Truncate((10^e-1)/9); for x in [1..9] do n:=a*x; f:=Factorization(n); if IsSquare(n) and not IsZero([x: x in [1..#f] | f[x][1] mod 4 eq 1]) or not IsSquare(n) and IsZero([x: x in [1..#f] | IsOdd(f[x][2]) and f[x][1] mod 4 eq 3]) then Append(~lst, n); end if; end for; end for; lst;

Crossrefs

Cf. A010785.

Sequence in context: A162709 A242875 A222897 * A387730 A323457 A011039

Adjacent sequences: A282452 A282453 A282454 * A282456 A282457 A282458

Keyword

nonn,base,fini,full

Author

Arkadiusz Wesolowski, Feb 15 2017

Status

approved