A031298 - OEIS

%I #32 Mar 07 2023 11:55:23

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

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

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

%N Triangle T(n,k): write n in base 10, reverse order of digits.

%C The length of n-th row is given in A055642(n). - _Reinhard Zumkeller_, Jul 04 2012

%C According to the formula for T(n,1), columns are numbered starting with 1. One might also number columns starting with the offset 0, as to have the coefficient of 10^k in column k. - _M. F. Hasler_, Jul 21 2013

%H Reinhard Zumkeller, <a href="/A031298/b031298.txt">Rows n = 0..2500 of triangle, flattened</a>

%F T(n,1) = A010879(n); T(n,A055642(n)) = A000030(n). - _Reinhard Zumkeller_, Jul 04 2012

%t Table[Reverse[IntegerDigits[n]],{n,0,50}]//Flatten (* _Harvey P. Dale_, Mar 07 2023 *)

%o (Haskell)

%o a031298 n k = a031298_tabf !! n !! k

%o a031298_row n = a031298_tabf !! n

%o a031298_tabf = iterate succ [0] where

%o    succ []     = [1]

%o    succ (9:ds) = 0 : succ ds

%o    succ (d:ds) = (d + 1) : ds

%o -- _Reinhard Zumkeller_, Jul 04 2012

%o (PARI) T(n,k)=n\10^(k-1)%10 \\ _M. F. Hasler_, Jul 21 2013

%Y Cf. A030308, A030341, A030386, A031235, A030567, A031007, A031045, A031087 for the base-2 to base-9 analogs.

%K nonn,base,tabf,less,look

%O 0,3

%A _Clark Kimberling_

%E Initial 0 and better name by _Philippe Deléham_, Oct 20 2011

%E Edited by _M. F. Hasler_, Jul 21 2013