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 A372909 Decimal expansion of Sum_{k>=0} (2^k + 1)/(4^k + 1). 3
 2, 1, 6, 2, 4, 9, 3, 2, 6, 5, 9, 7, 0, 7, 0, 3, 6, 6, 9, 3, 7, 7, 5, 1, 9, 4, 4, 1, 5, 9, 9, 1, 8, 6, 0, 4, 8, 3, 7, 1, 3, 2, 7, 1, 8, 1, 8, 6, 2, 8, 0, 2, 6, 2, 8, 0, 5, 8, 4, 9, 9, 7, 1, 1, 5, 9, 2, 7, 7, 1, 1, 5, 9, 9, 5, 7, 0, 9, 0, 9, 2, 9, 8, 3, 8 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..85. EXAMPLE 2.16249326597070366937751944159918604837132718186280262... MATHEMATICA s = Sum[(2^k + 1)/(4^k + 1), {k, 0, 1000}]; d = N[s, 100] First[RealDigits[d]] (* valid for first 200 digits; for more, change 1000 to 2000, etc. *) (* or *) RealDigits[Chop[N[-1 + (Log[3] - Pi + QPolyGamma[0, -I*Pi/Log[4], 1/4] + I*QPolyGamma[0, -I*Pi/Log[4], 2] - I*QPolyGamma[0, I*Pi/Log[4], 2])/Log[4], 120]], 10, 110][[1]] (* Vaclav Kotesovec, Jun 13 2024 *) CROSSREFS Cf. A372907, A372908, A372910, A372911. Sequence in context: A306549 A198870 A359273 * A365048 A050457 A195441 Adjacent sequences: A372906 A372907 A372908 * A372910 A372911 A372912 KEYWORD nonn,cons AUTHOR Clark Kimberling, Jun 12 2024 STATUS approved

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Last modified September 15 13:43 EDT 2024. Contains 375938 sequences. (Running on oeis4.)