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 A173665 Primes formed by the initial digits of the decimal expansion of 1/Catalan's constant. 0
 109, 1091, 109174406370390610145415947333, 10917440637039061014541594733338923249860501214082473450059137 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Primes found in 1/ A006752.   a(5) = 109174406...792972361 has 109 digits,   a(6) = 109174406...955798301 has 271 digits,   a(7) = 109174406...813410233 has 319 digits,   a(8) = 109174406...519744361 has 1223 digits. LINKS EXAMPLE 1/Catalan's constant = 1.09174406..., so a(1) = 109 ; a(2) = 1091. MAPLE Digits := 100; n0 := evalf(1/Catalan); for i from 1 to 100 do x := trunc(10^i*n0):   if isprime(x) then printf(`%d, `, x): fi: od: PROG (PARI) default(realprecision, 350); C=intnum(t=0, 1, atan(t)/t); for(k=1, default(realprecision), ispseudoprime(10^k\C) && print(10^k\C, " digits: ", k+1)) \\ M. F. Hasler, Nov 24 2010 CROSSREFS Cf. A006752, A014538. Sequence in context: A061699 A239720 A096214 * A059936 A262854 A232118 Adjacent sequences:  A173662 A173663 A173664 * A173666 A173667 A173668 KEYWORD nonn,base AUTHOR Michel Lagneau, Nov 24 2010 STATUS approved

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