login
A113799
Numbers k such that the k-th triangular number plus the reverse of k gives a square.
0
3, 36, 45, 423, 486, 558, 1377, 6690, 15540, 59460, 110694, 16867050, 443820753
OFFSET
1,1
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
Sequence in context: A158301 A105758 A214852 * A072682 A158207 A227032
KEYWORD
base,nonn
AUTHOR
Giovanni Resta, Jan 22 2006
STATUS
approved