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 A132800 Decimal expansion of Sum_{n >= 1} 1/3^prime(n). 7
 1, 5, 2, 7, 2, 6, 9, 0, 2, 7, 2, 5, 7, 2, 2, 4, 7, 1, 5, 2, 8, 1, 7, 5, 4, 1, 8, 7, 4, 4, 2, 5, 9, 1, 2, 4, 3, 0, 3, 4, 2, 3, 6, 4, 2, 7, 1, 4, 6, 3, 2, 9, 8, 5, 0, 8, 6, 2, 8, 8, 3, 7, 5, 3, 6, 7, 3, 2, 1, 3, 2, 2, 2, 3, 0, 9, 2, 1, 1, 0, 6, 2, 7, 0, 3, 7, 0, 9, 5, 9, 5, 5, 8, 9, 8, 7, 3, 9 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Equivalently, the real number in (0,1) having the characteristic function of the primes, A010051, as its base-3 expansion. - M. F. Hasler, Jul 04 2017. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..2000 FORMULA From Amiram Eldar, Aug 11 2020: (Start) Equals Sum_{k>=1} 1/A057901(k). Equals 2 * Sum_{k>=1} pi(k)/3^(k+1), where pi(k) = A000720(k). (End) EXAMPLE 0.15272690272572247152817541874425912430342364271463298508628837536732... MATHEMATICA RealDigits[Sum[1/3^Prime[k], {k, 100}], 10, 100][[1]] (* Vincenzo Librandi, Jul 05 2017 *) PROG (PARI) /* Sum of 1/m^p for primes p */ sumnp(n, m) = { local(s=0, a, j); for(x=1, n, s+=1./m^prime(x); ); a=Vec(Str(s)); for(j=3, 100, print1(eval(a[j])", ") ) } (PARI) suminf(n=1, 1/3^prime(n)) \\ Then: digits(%\.1^default(realprecision))[1..-3] to remove the last 2 digits. N.B.: Functions sumpos() and sumnum() yield much less accurate results. - M. F. Hasler, Jul 04 2017 CROSSREFS Cf. A000720, A051006 (analog for base 2), A132797 (analog for base 5), A010051 (characteristic function of the primes), A057901, A132806 (base 4). Sequence in context: A342002 A214969 A093591 * A183167 A115321 A127108 Adjacent sequences:  A132797 A132798 A132799 * A132801 A132802 A132803 KEYWORD cons,nonn AUTHOR Cino Hilliard, Nov 17 2007 EXTENSIONS Offset corrected R. J. Mathar, Jan 26 2009 Edited by M. F. Hasler, Jul 04 2017 STATUS approved

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Last modified April 22 13:29 EDT 2021. Contains 343177 sequences. (Running on oeis4.)