OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(7) = 2850 > 28 is the smallest triangular number beginning with 28 which is the seventh triangular number.
MAPLE
f:= proc(t) local k, s, r;
for k from 1 do
s:= ceil(sqrt(1+8*10^k*t));
if s::even then s:= s+1 fi;
r:= (s^2-1)/8 - 10^k*t;
if r < 10^k then
return 10^k*t + r
fi
od
end proc:
map(f, [seq(i*(i+1)/2, i=1..100)]); # Robert Israel, Mar 19 2018
CROSSREFS
KEYWORD
AUTHOR
Amarnath Murthy, Jul 31 2002
EXTENSIONS
Corrected and extended by Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 25 2003
STATUS
approved