A007512
Primes of the form floor(e*10^k), i.e., formed by concatenation of an initial segment of the decimal expansion of e.
Original entry on oeis.org
2, 271, 2718281, 2718281828459045235360287471352662497757247093699959574966967627724076630353547594571
Offset: 1
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
-
Digits := 110; n0 := evalf(E); for i from 1 to 100 do t1 := trunc(10^i*n0); if isprime(t1) then print(t1); fi; od:
-
c=exp(1);for(k=0,precision(c),ispseudoprime(c\.1^k) & print1(c\.1^k,",")) \\ M. F. Hasler, Sep 01 2013
Next term is a 1781-digit BPSW-probable prime 2718281828459045235...211151368350627526023. -
Randall L Rathbun, Feb 02 2002
A210704
Primes formed by initial digits of 3^(1/3) = A002581, i.e., of the form floor[3^(1/3)*10^k].
Original entry on oeis.org
144224957030740838232163, 144224957030740838232163831078010958839186925349935057754641619454168759682999733
Offset: 1
-
With[{cr3=RealDigits[CubeRoot[3],10,100][[1]]},Select[Table[FromDigits[Take[cr3,n]],{n,100}],PrimeQ]] (* Harvey P. Dale, Mar 30 2024 *)
-
(c=sqrtn(3,3),v=1/*set to 0 for indices instead of values*/)->for(k=0,precision(c),ispseudoprime(p=c\.1^k)&&print1([k,p][1+v]","))
A072952
Primes obtained as initial segments of the decimal expansion of the Euler-Mascheroni constant gamma = 0.5772... .
Original entry on oeis.org
5, 577, 5772156649015328606065120900824024310421
Offset: 1
a(2) = 577, since 577 is the second prime obtained as initial segment of the decimal expansion of Euler-Mascheroni constant gamma = 0.577215664... .
-
nn=200;With[{emc=RealDigits[EulerGamma,10,nn][[1]]},Select[Table[ FromDigits[ Take[emc,n]],{n,nn}],PrimeQ]] (* Harvey P. Dale, May 14 2013 *)
-
default(realprecision, 777); /* use that many digits */
A072952={(c=Euler, v=1/*set to 0 for indices (i.e., A065815) instead of values*/)->for(k=0, precision(c), ispseudoprime(p=c\.1^k)&&print1([k, p][1+v]", "))} \\ M. F. Hasler, Aug 31 2013
A119344
Integer lengths of Theodorus-primes: numbers n such that the concatenation of the first n decimal digits of the Theodorus's constant sqrt(3) is prime.
Original entry on oeis.org
2, 3, 19, 111, 116, 641, 5411, 170657
Offset: 1
sqrt(3) = 1.732050807568877..., so
a(1) = 2 (17 with 2 decimal digits is the 1st prime in the decimal expansion),
a(2) = 3 (173 with 3 decimal digits is the 2nd prime in the decimal expansion).
Cf.
A002194 (decimal expansion of sqrt(3)).
-
nn = 1000; digs = RealDigits[Sqrt[3], 10, nn][[1]]; n = 0; t = {}; Do[n = 10*n + digs[[d]]; If[PrimeQ[n], AppendTo[t, d]], {d, nn}]; t (* T. D. Noe, Dec 05 2011 *)
Module[{nn=171000,c},c=RealDigits[Sqrt[3],10,nn][[1]];Select[Range[ nn], PrimeQ[ FromDigits[Take[c,#]]]&]] (* Harvey P. Dale, May 13 2017 *)
A242835
Primes formed by the initial digits of the decimal expansion of the square root of 5.
Original entry on oeis.org
2, 223, 22360679774997896964091
Offset: 1
Decimal expansion of sqrt(5) begins: 2.23606797749978969640917366... - _Wesley Ivan Hurt_, May 26 2014
Cf.
A002163 (Decimal Expansion of sqrt(5)).
-
Module[{d=25,f},f=RealDigits[Sqrt[5],10,d][[1]];Select[ Table[ FromDigits[ Take[f,n]],{n,d}],PrimeQ]] (* Harvey P. Dale, Oct 29 2020 *)
Showing 1-5 of 5 results.
Comments