A346004 - OEIS

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A346004

If n even then n otherwise ((n+1)/2)^2.

0, 1, 2, 4, 4, 9, 6, 16, 8, 25, 10, 36, 12, 49, 14, 64, 16, 81, 18, 100, 20, 121, 22, 144, 24, 169, 26, 196, 28, 225, 30, 256, 32, 289, 34, 324, 36, 361, 38, 400, 40, 441, 42, 484, 44, 529, 46, 576, 48, 625, 50, 676, 52, 729, 54, 784, 56, 841, 58, 900, 60, 961, 62, 1024, 64, 1089

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

REFERENCES

J. H. Conway and R. K. Guy, The Book of Numbers, Copernicus Press, NY, 1996. Sequence can be seen in the circled numbers at foot of page 63.

LINKS

Paolo Xausa, Table of n, a(n) for n = 0..10000

Index entries for linear recurrences with constant coefficients, signature (0,3,0,-3,0,1).

FORMULA

G.f.: x*(-1-2*x-x^2+2*x^3) / ( (x-1)^3*(1+x)^3 ). - R. J. Mathar, Aug 05 2021

a(n) = ((n^2 + 6*n + 1) - (n-1)^2*(-1)^n)/8. - Aaron J Grech, Aug 27 2024

MATHEMATICA