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A179075
Concatenation of the first n numbers in base n.
0
6, 48, 436, 4855, 67146, 1120882, 21913032, 490328973, 12345678910, 345227121316, 10610896401084, 355457590375459, 12887297856859986, 502684312937210790, 20988295479420645136, 933876701895122362393, 44111544001370512713990, 2204350295349917301461848
OFFSET
2,1
COMMENTS
Always divisible by n, hence never prime.
FORMULA
a(n) = n + sum(i*(n^(n+1-i)), i=1..n-1).
EXAMPLE
a(2) = 110 (base 2) = 6 (base 10) = A047778(2).
a(3) = 1210 (base 3) = 48 (base 10) = A048435(3).
a(4) = 12310 (base 4) = 436 (base 10) = A048436(4).
a(5) = 123410 (base 5) = 4855 (base 10) = A048437(5).
a(11) = 123456789A10 (base 11) = 345227121316 (base 10).
a(16) = 123456789ABCDE10 (base 16) = 20988295479420645136 (base 10) = A048447(16).
PROG
(PARI) {for(n=2, 19, tlt=0;
for(i=1, n-1, tlt=tlt+i*(n^(n+1-i)));
print1(tlt+n, ", ") )} \\ Douglas Latimer, May 10 2012
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
Jonathan Vos Post, Jun 27 2010
EXTENSIONS
Edited (errors corrected, sequence extended) by Jon E. Schoenfield, Jul 05 2010 and Jul 06 2010
More terms from Douglas Latimer, May 10 2012
STATUS
approved