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A108706
Reverse these primes to get golden semiprimes.
1
3037, 3631, 10271, 92251, 334651, 3302191, 3349403, 3494923, 3500897, 3574297, 3971207, 9067837, 9150139, 11914451, 16077421, 16651111, 30842221, 32333971, 34747217, 71704051, 71900987, 76642031, 78818581, 92032757, 104062963
OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..336 (terms below 10^11)
EXAMPLE
The prime 3631 is in the sequence because reversed it is 1363 = 29*47 and abs(29*phi-47) = 0.077014... < 1.
MATHEMATICA
revDigits[n_] := FromDigits @ Reverse @ IntegerDigits[n]; goldQ[n_] := Module[{f = FactorInteger[n]}, If[Length[f] != 2, False, If[Max[f[[;; , 2]]] != 1, False, Abs[f[[2, 1]] - f[[1, 1]] * GoldenRatio] < 1]]]; seqQ[n_] := PrimeQ[n] && goldQ @ revDigits[n]; Select[Range[4*10^6], seqQ] (* Amiram Eldar, Nov 29 2019 *)
CROSSREFS
Cf. A108540.
Sequence in context: A254451 A205929 A145049 * A235218 A235662 A235666
KEYWORD
base,nonn
AUTHOR
Jason Earls, Jun 20 2005
EXTENSIONS
a(19)-a(25) from Donovan Johnson, Nov 11 2008
Offset corrected by Amiram Eldar, Nov 29 2019
STATUS
approved