A362270 Contribution to the OEIS

 

A362270 a(1) = 1, then subtract, multiply, and add 2, 3, 4; 5, 6, 7; ... in that order. 6

1, -1, -3, 1, -4, -24, -17, -25, -225, -215, -226, -2712, -2699, -2713, -40695, -40679, -40696, -732528, -732509, -732529, -15383109, -15383087, -15383110, -369194640, -369194615, -369194641, -9968255307, -9968255279, -9968255308, -299047659240, -299047659209, -299047659241, -9868572754953 (list; graph; refs; listen; history; edit; text; internal format)

OFFSET 1,3 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 = -1; a(3) = -1 * 3 = -3; a(4) = -3 + 4 = 1. 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 A362270_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) A362270_list = list(islice(A362270_gen(), 20)) # Chai Wah Wu, Apr 19 2023 CROSSREFS Other operation orders: A077382, A077383, A362269, A362271, A362272. Sequence in context: A112668 A016734 A272473 * A125846 A318382 A340190 Adjacent sequences: A362267 A362268 A362269 * A362271 A362272 A362273 KEYWORD sign AUTHOR James C. McMahon, Apr 13 2023 STATUS approved