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 A077814 a(n) = #{0<=k<=n: mod(kn,4)=2}. 3
 0, 0, 1, 1, 0, 1, 3, 2, 0, 2, 5, 3, 0, 3, 7, 4, 0, 4, 9, 5, 0, 5, 11, 6, 0, 6, 13, 7, 0, 7, 15, 8, 0, 8, 17, 9, 0, 9, 19, 10, 0, 10, 21, 11, 0, 11, 23, 12, 0, 12, 25, 13, 0, 13, 27, 14, 0, 14, 29, 15, 0, 15, 31, 16, 0, 16, 33, 17, 0, 17, 35, 18, 0, 18, 37, 19, 0, 19, 39, 20, 0, 20, 41, 21, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,7 COMMENTS Coefficients in the unique expansion of e/4 = Sum[a(n)/n!, n>=1], where a(n) satisfies 0<=a(n)6. a(n) = (-1)^((1-2*n-(-1)^n)/4)*((-1)^n-2*n*(-1)^((2*n+3+(-1)^n)/4)+n*(-1)^((1+(-1)^n)/2)+n*(-1)^((2*n+1+(-1)^n)/2)-1)/8. (End) EXAMPLE sum(i=1,10,a(i)/i!)=0.6795703813... exp(1)/4=0.679570457... MATHEMATICA a = Table[0, {i, 1, 50}]; x = Exp[1]/4; For[n = 2, n <= 51, n++, { an = 0; While [(x >= (1/n!)) && (an < (n - 1)), {an++, x = x - (1/n!)} ]}; a[[n - 1]] = an; ]; a CROSSREFS Cf. A009947, A087509, A087620. Sequence in context: A122861 A326045 A277097 * A131728 A373088 A075115 Adjacent sequences: A077811 A077812 A077813 * A077815 A077816 A077817 KEYWORD nonn,easy AUTHOR John W. Layman, Dec 03 2002 EXTENSIONS More terms from Benoit Cloitre, Dec 07 2002 STATUS approved

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Last modified August 11 07:51 EDT 2024. Contains 375059 sequences. (Running on oeis4.)