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Tetrahedral numbers written backwards.
1

%I #13 Apr 09 2015 11:07:08

%S 0,1,4,1,2,53,65,48,21,561,22,682,463,554,65,86,618,969,411,331,451,

%T 1771,4202,32,62,5292,6723,4563,604,5944,694,6545,4895,5456,417,777,

%U 6348,9319,889,6601,8411,14321,44231,9141,8151,51261,69271,42481,691,52802

%N Tetrahedral numbers written backwards.

%C Sorted: 0, 1, 2, 4, 21, 22, 32, 48, 53, 62, 65, 86, 122, 307, 331, 411, 417, 451, 463, 554, 561, 604, 618, 682, 691, 694, 777, 889, 969, 1771, ..., . - _Robert G. Wilson v_, Feb 24 2010

%H Alois P. Heinz, <a href="/A004161/b004161.txt">Table of n, a(n) for n = 0..10000</a>

%p a:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||(binomial(n+2,3))):

%p seq(a(n), n=0..50); # _Alois P. Heinz_, Apr 09 2015

%t f[n_] := FromDigits@ Reverse@ IntegerDigits[n (n + 1) (n + 2)/6]; Array[f, 49] (* _Robert G. Wilson v_, Feb 24 2010 *)

%Y Cf. A000292.

%K nonn,base,look

%O 0,3

%A _N. J. A. Sloane_

%E a(33)-a(49) from _Robert G. Wilson v_, Feb 24 2010