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A004158 Triangular numbers written backwards. 4
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 (list; graph; refs; listen; history; text; internal format)
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: A176231 A176230 A094445 * A221705 A303864 A058178

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

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Last modified March 21 22:19 EDT 2019. Contains 321382 sequences. (Running on oeis4.)