A074991 - OEIS

%I #21 Aug 07 2015 02:46:31

%S 4,41,78,115,152,189,226,263,2970,30337,33704,37071,40438,43805,47172,

%T 50539,53906,57273,60640,64007,67374,70741,74108,77475,80842,84209,

%U 87576,90943,94310,97677,101044,104411,107778,111145,114512

%N Concatenation of n, n+1, n+2 divided by 3.

%C If all the three numbers have the same number of digits then the terms are in A.P. with a common difference that follows a pattern with increase in number of digits. E.g. for n = 1 to 7 the common difference, c.d. = 37. For n = 10 to 97 c.d. = 3367, For three digit numbers from 100 to 997 it is 333667 etc.

%e a(4) = 456/3 = 152.

%p read("transforms") ;

%p A074991 := proc(n)

%p         digcatL([n,n+1,n+2]) ;

%p         %/3 ;

%p end proc:

%p seq(A074991(n),n=0..50) ; # _R. J. Mathar_, Oct 04 2011

%t f[n_] := FromDigits@ Flatten@ IntegerDigits[{n, n + 1, n + 2}]/3; Array[f, 26, 0] (* _Robert G. Wilson v_ *)

%Y Cf. A074992.

%Y Equals (1/3) A001703.

%K base,nonn

%O 0,1

%A _Amarnath Murthy_, Aug 31 2002

%E Incorrect conjecture deleted by _Colin Barker_, Sep 26 2013