A113799 Numbers k such that the k-th triangular number plus the reverse of k gives a square.

3, 36, 45, 423, 486, 558, 1377, 6690, 15540, 59460, 110694, 16867050, 443820753

Offset

1,1

Links

Table of n, a(n) for n=1..13.

Example

T(423) + 324 = 300^2.

Mathematica

testQ[n_] := IntegerQ[Sqrt[n(n+1)/2 + FromDigits@Reverse@IntegerDigits@n]]; lst = Select[Range[10^5], testQ]

Crossrefs

Cf. A000217, A004086.

Sequence in context: A158301 A105758 A214852 * A072682 A158207 A227032

Adjacent sequences: A113796 A113797 A113798 * A113800 A113801 A113802

Keyword

base,nonn

Author

Giovanni Resta, Jan 22 2006

Status

approved