A171950 a(1)=1. a(n) = the absolute difference between (the sum of previous terms) and A000217(n-2), n>1.
1, 1, 1, 0, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68
Offset: 1
Links
- Index entries for linear recurrences with constant coefficients, signature (2,-1).
Programs
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Magma
[1,1,1,0] cat [n-2: n in [5..70]]; // G. C. Greubel, Apr 03 2019
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Mathematica
LinearRecurrence[{2,-1},{1,1,1,0,3,4},70] (* Harvey P. Dale, Dec 10 2015;; a(1)=1 amended by Georg Fischer, Apr 03 2019 *) -
PARI
a(n)=if(n>4,n-2,n<4) \\ Charles R Greathouse IV, Oct 27 2011
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Sage
[1,1,1,0]+[n-2 for n in (5..70)] # G. C. Greubel, Apr 03 2019
Formula
a(n) = |Sum_{i=1..n-1} a(i) - A000217(n-2)|, n>1.
a(n) = n-2, n>=5. - R. J. Mathar, Oct 26 2010
Extensions
Zero inserted, precise indices added in definition, keyword:less and two formulas added - R. J. Mathar, Oct 26 2010
A171950 and A181440 are two different edited versions of a sequence submitted by Giovanni Teofilatto. - N. J. A. Sloane, Oct 29 2010