A274094 a(0)=0; thereafter (-1)^(n+1)*n appears n times.
0, 1, -2, -2, 3, 3, 3, -4, -4, -4, -4, 5, 5, 5, 5, 5, -6, -6, -6, -6, -6, -6, 7, 7, 7, 7, 7, 7, 7, -8, -8, -8, -8, -8, -8, -8, -8, 9, 9, 9, 9, 9, 9, 9, 9, 9, -10, -10, -10, -10, -10, -10, -10, -10, -10, -10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, -12, -12, -12, -12, -12, -12, -12, -12, -12, -12
Offset: 0
Keywords
Links
- Chai Wah Wu, Table of n, a(n) for n = 0..10011
Programs
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Maple
s1:=[0]; for n from 1 to 15 do for i from 1 to n do s1:=[op(s1),(-1)^(n+1)*n]; od: od: s1;
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Mathematica
Join[{0}, Flatten[Table[(-1)^(n+1)*n, {n, 15}, {n}]]] (* Paolo Xausa, Sep 30 2024 *) Join[{0},Flatten[Table[PadRight[{},n,(-1)^(n+1) n],{n,15}]]] (* Harvey P. Dale, Nov 28 2024 *) -
Python
A274094_list = [0]+ [i for n in range(1,142) for i in [n if n % 2 else -n]*n] # Chai Wah Wu, Jun 11 2016
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Python
from math import isqrt def A274094(n): return m if (m:=isqrt(n<<3)+1>>1)&1 else -m # Chai Wah Wu, Nov 05 2024