OFFSET
1,1
COMMENTS
Conjecture: the Benford law limit is 2=Sum[N[Log[10, 1 + 1/d[[n]]]], {n, 1, Length[d]}]^2/(( #totalprimes/#totalPrimes)). At 50000 primes total it is 2.05931. - Roger L. Bagula and Gary W. Adamson, Jul 02 2008
Presumably this does not satisfy Benford's law. - N. J. A. Sloane, Feb 09 2017
LINKS
Indranil Ghosh, Table of n, a(n) for n = 1..25000 (terms 1..206 from Roger L. Bagula and Gary W. Adamson)
Eric Weisstein's World of Mathematics, Benford's Law.
EXAMPLE
The prime 107 in reverse is 701 which is prime.
MATHEMATICA
b = Flatten[Table[If[PrimeQ[Sum[IntegerDigits[Prime[n]][[i]]*10^(i - 1), {i, 1, Length[IntegerDigits[Prime[n]]]}]], Sum[IntegerDigits[Prime[n]][[i]]*10^(i - 1), {i, 1, Length[IntegerDigits[Prime[n]]]}], {}], {n, 1, 1000}]] (* Roger L. Bagula and Gary W. Adamson, Jul 02 2008 *)
Select[FromDigits[Reverse[IntegerDigits[#]]]&/@Prime[Range[300]], PrimeQ] (* Harvey P. Dale, May 05 2015 *)
PROG
(PARI) r(n) = forprime(x=1, n, y=eval(rev(x)); if(isprime(y), print1(y", "))) \ Get the reverse of the input string rev(str) = { local(tmp, j, s); tmp = Vec(Str(str)); s=""; forstep(j=length(tmp), 1, -1, s=concat(s, tmp[j])); return(s) }
(Haskell)
a095180 n = a095180_list !! (n-1)
a095180_list =filter ((== 1) . a010051) a004087_list
-- Reinhard Zumkeller, Oct 14 2011
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Cino Hilliard, Jun 21 2004
STATUS
approved