A004158 Triangular numbers written backwards.

0, 1, 3, 6, 1, 51, 12, 82, 63, 54, 55, 66, 87, 19, 501, 21, 631, 351, 171, 91, 12, 132, 352, 672, 3, 523, 153, 873, 604, 534, 564, 694, 825, 165, 595, 36, 666, 307, 147, 87, 28, 168, 309, 649, 99, 5301, 1801, 8211, 6711, 5221, 5721, 6231, 8731, 1341, 5841, 451

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..10000

Formula

a(n) = A004086(A000217(n)). - Michel Marcus, Apr 05 2014

Maple

a:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||(n*(n+1)/2)):
seq(a(n), n=0..60);  # Alois P. Heinz, Apr 09 2015

Mathematica

Table[FromDigits[Reverse[IntegerDigits[n (n + 1) / 2]]], {n, 0, 50}] (* Vincenzo Librandi, Jan 21 2016 *)

Prog

(Magma) [Seqint(Reverse(Intseq(Binomial((n+1), 2)))): n in [0..60]]; // Vincenzo Librandi, Jan 21 2016

Crossrefs

Sequence in context: A176230 A335227 A094445 * A221705 A332505 A303864

Adjacent sequences: A004155 A004156 A004157 * A004159 A004160 A004161

Keyword

nonn,base,look

Author

N. J. A. Sloane

Extensions

Initial 0 and terms after a(46) from Eric M. Schmidt, Apr 04 2014

Status

approved