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A248961 Sums of wrecker ball sequences starting with n. 4
0, 1, -2, 5, -292, -241, 14, -437861, -28, -1, 30, 313, -4472, -4223, -2, 55, 3252, -214246256269, -70, -27, 5260887648, 91, -538, -193, -132, -864538549823, -22, 27, 140, 40053, 53088613819206, 86166834699, 86167898716, 86168962733, 86170026754, 49, 204 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

a(n) = A248973(n,A228474(n)) = sum of row n in triangle A248939;

a(A000217(n)) = A000330(n).

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..1000

Gordon Hamilton, Wrecker Ball Sequences, Video, 2013

EXAMPLE

a(1) = 1+0 = 1;

a(2) = 2+1-1-4+0 = -2;

a(3) = 3+2+0 = 5;

a(4) = 4+3+1-2+2-3-9-16-8-17-7-18-6+7+21+6-10-27-45-26-46-25-47-24+0 = -292;

a(5) = 5+4+2-1+3-2-8-15-7-16-6-17-5+8+22+7-9-26-44-25-45-24-46-... = -241;

a(6) = 6+5+3+0 = 14;

a(7) = 7+6+4+1-3+2-4+3-5-14-24-13-1+12-2+13+29+46+28+9-11+10-... = -437861;

a(8) = 8+7+5+2-2+3-3+4-4-13-23-12+0 = -28;

a(9) = 9+8+6+3-1+4-2+5-3-12-22-11+1+14+0 = -1.

PROG

(Haskell)

import Data.IntSet (singleton, member, insert)

a248961 n = addup 1 n 0 $ singleton n where

   addup _ 0 sum _ = sum

   addup k x sum s = addup (k + 1) y (sum + x) (insert y s) where

                     y = x + (if (x - j) `member` s then j else -j)

                     j = k * signum x

CROSSREFS

Cf. A248939,  A248973, A228474, A000217, A000330.

Sequence in context: A042341 A300900 A016088 * A042909 A270476 A183129

Adjacent sequences:  A248958 A248959 A248960 * A248962 A248963 A248964

KEYWORD

sign

AUTHOR

Reinhard Zumkeller, Oct 18 2014

STATUS

approved

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Last modified October 23 22:04 EDT 2018. Contains 316541 sequences. (Running on oeis4.)