login
A228967
Table read by rows; T(n,k) = 2n for k = 1, T(n,k) = 9n for k = 2.
1
2, 9, 4, 18, 6, 27, 8, 36, 10, 45, 12, 54, 14, 63, 16, 72, 18, 81, 20, 90, 22, 99, 24, 108, 26, 117, 28, 126, 30, 135, 32, 144, 34, 153, 36, 162, 38, 171, 40, 180, 42, 189, 44, 198, 46, 207, 48, 216, 50, 225, 52, 234, 54, 243, 56, 252, 58, 261, 60, 270, 62, 279, 64, 288
OFFSET
1,1
COMMENTS
The members of each pair [T(n,1),T(n,2)] create the same sequence of curvatures (rounded down) of circles after offset of the first 4 terms. See the pattern construction rule and formulas in links. Let the legs' length a = b = T(n,k). See also illustration in links; T(1,1) and T(1,2) create the same sequence, but it is different from the one created by both T(2,1), and T(2,2). Are they have repeated sequences between pairs?
Positive terms of A005843 and positive terms of A008591 interleaved. - Omar E. Pol, Sep 14 2013
FORMULA
a(n) = 2a(n-2) - a(n-4). - Charles R Greathouse IV, Sep 10 2013
EXAMPLE
Table begins:
n/k 1 2
1 2 9
2 4 18
3 6 27
4 8 36
...
MATHEMATICA
LinearRecurrence[{0, 2, 0, -1}, {2, 9, 4, 18}, 80] (* Harvey P. Dale, Sep 21 2019 *)
PROG
(PARI) vector(80, n, (n+1)\2*if(n%2, 2, 9)) \\ Charles R Greathouse IV, Sep 10 2013
CROSSREFS
Sequence in context: A080803 A370500 A339316 * A342661 A213821 A022157
KEYWORD
nonn,easy,tabf
AUTHOR
Kival Ngaokrajang, Sep 10 2013
EXTENSIONS
Corrected by Charles R Greathouse IV, Sep 10 2013
STATUS
approved