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

1,5

Links

Table of n, a(n) for n=1..70.

Index entries for linear recurrences with constant coefficients, signature (2,-1).

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

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 *)

Prog

(PARI) a(n)=if(n>4, n-2, n<4) \\ Charles R Greathouse IV, Oct 27 2011
(Magma) [1, 1, 1, 0] cat [n-2: n in [5..70]]; // G. C. Greubel, Apr 03 2019
(Sage) [1, 1, 1, 0]+[n-2 for n in (5..70)] # G. C. Greubel, Apr 03 2019

Crossrefs

Cf. A000217, A065475.

Sequence in context: A333838 A030544 A141213 * A184985 A114637 A009056

Adjacent sequences: A171947 A171948 A171949 * A171951 A171952 A171953

Keyword

easy,nonn,less

Author

Giovanni Teofilatto, Oct 20 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

Status

approved