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A205084
a(n)=n 4's sandwiched between two 1's.
0
11, 141, 1441, 14441, 144441, 1444441, 14444441, 144444441, 1444444441, 14444444441, 144444444441, 1444444444441, 14444444444441, 144444444444441, 1444444444444441, 14444444444444441, 144444444444444441, 1444444444444444441, 14444444444444444441
OFFSET
0,1
FORMULA
a(0)=11, a(n)=10*a(n-1)+31.
a(n) = (130*10^n-31)/9 (see PARI's code by Charles R Greathouse IV).
MATHEMATICA
a[0]=11; a[n_]:=a[n-1]*10+31; Table[a[n], {n, 0, 44}]
PROG
(PARI) a(n)=(130*10^n-31)/9 \\ Charles R Greathouse IV, Jan 23 2012
CROSSREFS
Sequence in context: A024296 A324084 A141907 * A083078 A048965 A218502
KEYWORD
nonn,easy,base,less
AUTHOR
STATUS
approved