A362271 a(1) = 1, then add, subtract and multiply 2, 3, 4; 5, 6, 7; ... in that order.

1, 3, 0, 0, 5, -1, -7, 1, -8, -80, -69, -81, -1053, -1039, -1054, -16864, -16847, -16865, -320435, -320415, -320436, -7049592, -7049569, -7049593, -176239825, -176239799, -176239826, -4934715128, -4934715099, -4934715129, -152976168999, -152976168967, -152976169000

Offset

1,2

Links

Table of n, a(n) for n=1..33.

Formula

a(1)=1; for n > 1,

a(n) = a(n-1) + n if n mod 3 = 2,

a(n-1) - n if n mod 3 = 0,

a(n-1) * n if n mod 3 = 1.

Example

a(2) = 1 + 2 = 3;
a(3) = 3 - 3 = 0;
a(4) = 0 * 4 = 0.

Mathematica

FoldList[If[Mod[#2, 3]==2, #1+#2, If[Mod[#2, 3]==0, #1-#2, #1*#2]]&, 1, Range[2, 33]] (* James C. McMahon, Oct 09 2023 *)

Prog

(Python)
from itertools import count, islice
def A362271_gen(): # generator of terms
    yield (a:=1)
    for n in count(2, 3):
        yield (a:=a+n)
        yield (a:=a-n-1)
        yield (a:=a*(n+2))
A362271_list = list(islice(A362271_gen(), 20)) # Chai Wah Wu, Apr 19 2023

Crossrefs

Other operation orders: A077382, A077383, A362269, A362270, A362272.

Sequence in context: A092669 A255986 A011400 * A115013 A072736 A135090

Adjacent sequences: A362268 A362269 A362270 * A362272 A362273 A362274

Keyword

sign

Author

James C. McMahon, Apr 13 2023

Status

approved