OFFSET
1,1
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..10000 (terms 1..200 from Shyam Sunder Gupta)
EXAMPLE
a(4)=210 because 210 is the smallest triangular number that ends with 4th triangular number i.e. 10.
MATHEMATICA
TriangularQ[n_Integer?Positive] := IntegerQ[Sqrt[8*n + 1]]; f[n_] := (k = 1; While[a = ToExpression[ ToString[k] <> ToString[n]]; ! TriangularQ[a], k++ ]; a); Table[f[ n*(n + 1)/2], {n, 1, 50}]
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Shyam Sunder Gupta, Sep 17 2013
STATUS
approved