This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A180352 A permutation of Motzkin numbers by reversal of indices in blocks of length 7. 1
 127, 51, 21, 9, 4, 2, 1, 113634, 41835, 15511, 5798, 2188, 835, 323, 142547559, 50852019, 18199284, 6536382, 2356779, 853467, 310572, 208023278209, 73007772802, 25669818476, 9043402501, 3192727797, 1129760415, 400763223 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The sequence shows A001006(7) down to A001006(1), then A001006(14) down to A001006(8), etc., varying the index in a sawtooth pattern. When I initially logged in to use the OEIS, it 'pre-loaded' the search box with a sequence. The seven terms 127,51,21,9,4,2,1 are obtained from that original one by reversing the terms. "Periodic" term reversals of this sort are routinely encountered when writing out convolution sums. LINKS FORMULA Let r(n) = 7, 6, 5 ,4, 3, 2, 1 (n>=1), extended with r(n+7)=7+r(n), then a(n) = A001006(r(n)). PROG (Sage) A180352 = lambda n: A001006(7*((n-1)//7+1)-((n-1) % 7)) # D. S. McNeil, Dec 06 2010 CROSSREFS Cf. A001006, A073794 Sequence in context: A051335 A186995 A145586 * A217557 A320571 A082456 Adjacent sequences:  A180349 A180350 A180351 * A180353 A180354 A180355 KEYWORD less,easy,nonn AUTHOR Matt Insall (insall(AT)mst.edu), Aug 29 2010 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 12 22:06 EST 2019. Contains 329963 sequences. (Running on oeis4.)