|
|
A091781
|
|
Beginning with 1, sum of all possible strings obtained as concatenation of previous (successive) terms.
|
|
2
|
|
|
1, 1, 13, 1252, 12396260, 1239500874377560, 12395008619813008676506120642920, 1239500861981300743700524626536099160068958504069412048965143360, 12395008619813007437005246265360867650603386910607355428445004411155507757831706693304721638824892440620626536624708440686290240
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
COMMENTS
|
a(n) is the sum of n(n+1)/2 such strings. a(n) has roughly 2^(n-1) decimal digits. - R. J. Mathar, Jul 26 2007
|
|
LINKS
|
|
|
EXAMPLE
|
a(0) = 1 hence a(1) = 1, a(2) = (1)+(1)+ (11) = 13, a(3) = (1) +(1) +(13) + (11) + (113) + (1113) = 1252.
|
|
MAPLE
|
A055642 := proc(n) if n <= 1 then 1 ; else ilog10(n)+ 1; fi ; end: Lcat := proc(L, i, j) local resul, k ; resul := 0 ; for k in op(i..j, L) do resul := resul*10^A055642(k)+k ; od ; RETURN(resul) ; end: A091781 := proc(nmax) local a, anxt, n, i, j; a := [1] ; for n from 1 to nmax do anxt := 0 ; for i from 1 to nops(a) do for j from i to nops(a) do anxt := anxt+Lcat(a, i, j) : od ; od ; a := [op(a), anxt] ; od; RETURN(a) ; end: A091781(9) ; # R. J. Mathar, Jul 26 2007
|
|
CROSSREFS
|
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
a(4) and a(5) from Donald Sampson (marsquo(AT)hotmail.com), Sep 17 2004
|
|
STATUS
|
approved
|
|
|
|