OFFSET
1,1
LINKS
Shyam Sunder Gupta, Table of n, a(n) for n = 1..500
EXAMPLE
a(4)=105 because 105 is triangular number that begins with 4th triangular number i.e. 10.
MATHEMATICA
TriangularQ[n_Integer?Positive] := IntegerQ[Sqrt[8*n + 1]]; q = {}; Do[x = n*(n + 1)/2; Do[a = IntegerLength[m]; c = x*10^a + m; If[TriangularQ[c], AppendTo[q, c]; Break[]], {m, 1, 10000}], {n, 1, 100}]; q
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Shyam Sunder Gupta, Sep 17 2013
STATUS
approved