A038457 - OEIS

%I #10 Mar 22 2020 15:54:30

%S 0,0,0,0,1,4,1,6,3,1,0,0,1,8,4,1,5,2,0,1,2,1,1,4,3,2,2,5,2,1,1,2,3,4,

%T 0,6,0,4,6,7,8,7,6,3,9,4,0,7,5,4,4,5,7,0,4,1,5,2,0,1,1,0,2,4,2,3,1,6,

%U 4,3,3,4,6,1,3,2,4,0,2,3,3,2,0,3,3,2,2,5,3,1,1,2,4,3,1,4,2,1,3,4,5

%N |First digit-last digit| for triangular numbers.

%F a(n) = A040163(A000217(n)). - _Michel Marcus_, Sep 27 2013

%t Abs[IntegerDigits[#][[1]]-IntegerDigits[#][[-1]]]&/@Accumulate[ Range[ 0,120]] (* _Harvey P. Dale_, Mar 22 2020 *)

%Y Cf. A000217.

%K easy,nonn,base

%O 0,6

%A _Felice Russo_