A077383 a(1) = 1, then add, multiply and subtract 2, 3, 4; 5, 6, 7; ... in that order.

1, 3, 9, 5, 10, 60, 53, 61, 549, 539, 550, 6600, 6587, 6601, 99015, 98999, 99016, 1782288, 1782269, 1782289, 37428069, 37428047, 37428070, 898273680, 898273655, 898273681, 24253389387, 24253389359, 24253389388, 727601681640, 727601681609

Offset

1,2

Links

Table of n, a(n) for n=1..31.

Example

a(2) = a(1) + 2 = 3, a(3) = 3*3 = 9, a(4) = 9 - 4 = 5, a(5) = 5 + 5 = 10, etc.

Maple

a := proc(n) if n=1 then 1 elif n mod 3 = 2 then a(n-1)+n elif n mod 3 = 0 then n*a(n-1) elif n mod 3 = 1 then a(n-1)-n else fi end: # Emeric Deutsch, Dec 17 2003

Mathematica

FoldList[If[Mod[#2, 3]==2, #1+#2, If[Mod[#2, 3]==0, #1*#2, #1-#2]]&, 1, Range[2, 31]] (* James C. McMahon, Oct 10 2023 *)

Prog

(Python)
from itertools import count, islice
def A077383_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)
A077383_list = list(islice(A077383_gen(), 20)) # Chai Wah Wu, Apr 19 2023

Crossrefs

Other operation orders: A077382, A077384, A362269, A362270, A362271, A362272.

Sequence in context: A096418 A100811 A223652 * A084492 A327762 A327460

Adjacent sequences: A077380 A077381 A077382 * A077384 A077385 A077386

Keyword

nonn

Author

Amarnath Murthy, Nov 06 2002

Extensions

More terms from Emeric Deutsch, Dec 17 2003

Status

approved