A362269 a(1) = 1, then subtract, add, and multiply 2, 3, 4; 5, 6, 7; ... in that order.

1, -1, 2, 8, 3, 9, 63, 55, 64, 640, 629, 641, 8333, 8319, 8334, 133344, 133327, 133345, 2533555, 2533535, 2533556, 55738232, 55738209, 55738233, 1393455825, 1393455799, 1393455826, 39016763128, 39016763099, 39016763129

Offset

1,3

Links

Delbert L. Johnson, Table of n, a(n) for n = 1..1143

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 = -1;
a(3) = -1 + 3 =  2;
a(4) =  2 * 4 =  8.

Mathematica

FoldList[If[Mod[#2, 3]==2, #1-#2, If[Mod[#2, 3]==0, #1+#2, #1*#2]]&, 1, Range[2, 30]] (* James C. McMahon, Oct 08 2023 *)

Prog

(Python)
from itertools import count, islice
def A362269_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))
A362269_list = list(islice(A362269_gen(), 20)) # Chai Wah Wu, Apr 19 2023

Crossrefs

Other operation orders: A077382, A077383, A362270, A362271, A362272.

Sequence in context: A011057 A082236 A337822 * A262027 A328487 A083003

Adjacent sequences: A362266 A362267 A362268 * A362270 A362271 A362272

Keyword

sign

Author

James C. McMahon, Apr 13 2023

Status

approved