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A256963
Partial sums of A005210.
1
1, 2, 2, 4, 7, 8, 8, 14, 17, 22, 22, 24, 35, 36, 44, 50, 55, 56, 64, 74, 79, 82, 92, 100, 103, 110, 124, 124, 125, 154, 154, 180, 187, 212, 216, 234, 245, 254, 262, 276, 287, 290, 308, 328, 339, 344, 364, 382, 391, 396, 424, 438, 455, 464, 476, 502, 509, 510
OFFSET
1,2
COMMENTS
It is conjectured that a(n) grows like n^2/6.
REFERENCES
Popular Computing (Calabasas, CA), Z-Sequences, Vol. 4 (No. 42, Sep 1976), pp. 12-16.
LINKS
Popular Computing (Calabasas, CA), Z-Sequences, continued. Annotated and scanned copy of pages 14, 15, 16, 18 of Vol. 5 (No. 56, Nov 1977).
MAPLE
b:= proc(n) option remember;
`if`(n<3, 1, abs(b(n-1)+2*b(n-2)-n))
end:
a:= proc(n) option remember;
b(n)+`if`(n>1, a(n-1), 0)
end:
seq(a(n), n=1..60); # Alois P. Heinz, Apr 16 2015
MATHEMATICA
Accumulate[RecurrenceTable[{a[1] == a[2] == 1, a[n] == Abs[a[n-1] + 2a[n-2] - n]}, a, {n, 1, 100}]] (* Jean-François Alcover, Nov 23 2020 *)
CROSSREFS
Cf. A005210.
Sequence in context: A065968 A105669 A338917 * A355306 A019657 A134791
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Apr 16 2015
STATUS
approved