OFFSET
0,2
COMMENTS
It appears that the number of trailing zeros in a(n) is A191610(n). - Robert Israel, Nov 24 2015
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..43
FORMULA
10^n|a(n) for n>=0; 12*(10)^(n)|a(n) n>=2. - G. C. Greubel, Nov 21 2015
a(n) ~ c * 11^(n*(n+1)/2), where c = Product_{k>=1} (1-1/11^k) = 0.900832706809715279949862694760647744762491192216... . - Vaclav Kotesovec, Nov 21 2015
E.g.f. E(x) satisfies E'(x) = 11 E(11 x) - E(x). - Robert Israel, Nov 24 2015
Equals 11^(binomial(n+1,2))*(1/11;1/11)_{n}, where (a;q)_{n} is the q-Pochhammer symbol. - G. C. Greubel, Dec 24 2015
G.f.: Sum_{n>=0} 11^(n*(n+1)/2)*x^n / Product_{k=0..n} (1 + 11^k*x). - Ilya Gutkovskiy, May 22 2017
Sum_{n>=0} (-1)^n/a(n) = A132267. - Amiram Eldar, May 07 2023
MAPLE
seq(mul(11^i-1, i=1..n), n=0..20; # Robert Israel, Nov 24 2015
MATHEMATICA
FoldList[Times, 1, 11^Range[10]-1] (* Harvey P. Dale, Aug 13 2013 *)
Abs@QPochhammer[11, 11, Range[0, 40]] (* G. C. Greubel, Nov 24 2015 *)
PROG
(PARI) a(n)=prod(i=1, n, 11^i-1) \\ Anders Hellström, Nov 21 2015
(Magma) [1] cat [&*[11^k-1: k in [1..n]]: n in [1..11]]; // Vincenzo Librandi, Dec 24 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved