A179075 - OEIS

%I #15 May 28 2016 12:53:45

%S 6,48,436,4855,67146,1120882,21913032,490328973,12345678910,

%T 345227121316,10610896401084,355457590375459,12887297856859986,

%U 502684312937210790,20988295479420645136,933876701895122362393,44111544001370512713990,2204350295349917301461848

%N Concatenation of the first n numbers in base n.

%C Always divisible by n, hence never prime.

%F a(n) = n + sum(i*(n^(n+1-i)), i=1..n-1).

%e a(2) = 110 (base 2) = 6 (base 10) = A047778(2).

%e a(3) = 1210 (base 3) = 48 (base 10) = A048435(3).

%e a(4) = 12310 (base 4) = 436 (base 10) = A048436(4).

%e a(5) = 123410 (base 5) = 4855 (base 10) = A048437(5).

%e a(11) = 123456789A10 (base 11) = 345227121316 (base 10).

%e a(16) = 123456789ABCDE10 (base 16) = 20988295479420645136 (base 10) = A048447(16).

%o (PARI) {for(n=2,19,tlt=0;

%o for(i=1,n-1,tlt=tlt+i*(n^(n+1-i)));

%o print1(tlt+n, ", ") )} \\ _Douglas Latimer_, May 10 2012

%Y Cf. A047778, A048435-A048447, A179069.

%K easy,nonn,base

%O 2,1

%A _Jonathan Vos Post_, Jun 27 2010

%E Edited (errors corrected, sequence extended) by _Jon E. Schoenfield_, Jul 05 2010 and Jul 06 2010

%E More terms from _Douglas Latimer_, May 10 2012