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A253607 First differences of A253580, when the tree is seen as flattened list. 6
1, -1, 2, 1, -2, -1, 2, 2, 1, -2, -2, -1, 2, 2, 2, 1, -2, -2, -2, -1, 2, 2, 2, 2, 1, -2, -2, -2, -2, -1, 2, 2, 2, 2, 2, 1, -2, -2, -2, -2, -2, -1, 2, 2, 2, 2, 2, 2, 1, -2, -2, -2, -2, -2, -2, -1, 2, 2, 2, 2, 2, 2, 2, 1, -2, -2, -2, -2, -2, -2, -2, -1, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

a(n) != 0 and -2 <= a(n) <= +2.

a(n) = 1 iff A253580(n+1) = A253580(n) + 1, marked with X in the table below, where also the erasure of pairs of consecutive terms in A253580 is illustrated;

a(A005563(n)) = 1; a(A028387(n)) = -1;

a(A061885(n)) > 0; a(A064801(n)) < 0.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

√Čric Angelini, More fractal trees - and erasures, SeqFan list, Jan 04 2015.

EXAMPLE

.   n | A253580(n) | a(n) | erased | reappearing

.  ---+------------+------+--------+-------------

.   0 |    X    0  |   1  |      0 |

.   1 |    X    1  |  -1  |      1 |

.   2 |         0  |   2  |        |           0

.   3 |    X    2  |   1  |      2 |

.   4 |    X    3  |  -2  |      3 |

.   5 |         1  |  -1  |        |           1

.   6 |         0  |   2  |        |           0

.   7 |         2  |   2  |        |           2

.   8 |    X    4  |   1  |      4 |

.   9 |    X    5  |  -2  |      5 |

.  10 |         3  |  -2  |        |           3

.  11 |         1  |  -1  |        |           1

.  12 |         0  |   2  |        |           0

.  13 |         2  |   2  |        |           2

.  14 |         4  |   2  |        |           4

.  15 |    X    6  |   1  |      6 |

.  16 |    X    7  |  -2  |      7 |

.  17 |         5  |  -2  |        |           5

.  18 |         3  |  -2  |        |           3

.  19 |         1  |  -1  |        |           1

.  20 |         0  |   2  |        |           0

.  21 |         2  |   2  |        |           2

.  22 |         4  |   2  |        |           4

.  23 |         6  |   2  |        |           6

.  24 |    X    8  |   1  |      8 |

.  25 |    X    9  |  -2  |      9 |             .

PROG

(Haskell)

a253607 n = a253607_list !! n

a253607_list = zipWith (-) (tail a253580_list) a253580_list

CROSSREFS

Cf. A253580, A005563, A028387, A061885, A064801.

Sequence in context: A076371 A175044 A106149 * A212179 A257023 A238894

Adjacent sequences:  A253604 A253605 A253606 * A253608 A253609 A253610

KEYWORD

sign

AUTHOR

Reinhard Zumkeller, Jan 05 2015

STATUS

approved

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Last modified April 9 10:52 EDT 2020. Contains 333348 sequences. (Running on oeis4.)