This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A168110 Palindromic primes in base 8 which are also emirps (A006567) in base 10. 1
 73, 97, 113, 12547, 12611, 13259, 13523, 14107, 14563, 14891, 15667, 15731, 30367, 31799, 31991, 312073, 318281, 350033, 359377, 366169, 371353, 372377, 383833, 392153, 393761, 397921, 792131, 796291, 936227, 936739, 948707, 966379, 992947, 1005427, 1008563, 1029883, 1043899, 1048571, 1311749, 1313797, 1340357, 1358029 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS What is a good way in the OEIS to show other such pairs of bases analogous to this? LINKS FORMULA A029976 INTERSECTION A006567. EXAMPLE a(1) = 73 because 73 (base 8) = 111 (which is a palindrome), and R(73) = 37 which is a different prime (base 10). a(2) = 97 because 97 (base 8) = 141 (which is a palindrome), and R(97) = 79 which is a different prime (base 10). a(3) = 113 because 113 (base 8) = 161 (which is a palindrome), and R(113) = 311 which is a different prime (base 10). a(4) = 12547 because 12547 (base 8) = 30403 (which is a palindrome), and R(12547) = 74521 which is a different prime (base 10). MAPLE isA006567 := proc(p) local r; if isprime(p) then r := digrev(p) ; r <> p and isprime(r) ; else false; end if; end proc: isA029803 := proc(n) local dgs, d; dgs := convert(n, base, 8) ; for d from 1 to nops(dgs)/2 do if op(d, dgs) <> op(-d, dgs) then return false; end if; end do ; return true; end proc: isA029976 := proc(n) isprime(n) and isA029803(n) ; end proc: isA168110 := proc(p) isA029976(p) and isA006567(p) ; end proc: A168110 := proc(n) option remember ; local a; if n = 1 then 73 ; else a := nextprime(procname(n-1)) ; while not isA168110(a) do a := nextprime(a) ; end do ; return a; end if; end proc: seq(A168110(n), n=1..30) ; # R. J. Mathar, Dec 06 2009 MATHEMATICA okQ[n_]:=Module[{fridn=FromDigits[Reverse[IntegerDigits[n]]], idn8= IntegerDigits[n, 8]}, fridn!=n&&PrimeQ[fridn]&&idn8==Reverse[idn8]]; Select[Prime[Range[75000]], okQ] (* Harvey P. Dale, Aug 10 2011 *) CROSSREFS Cf. A000040, A004086, A006567, A007094, A029976. Sequence in context: A152308 A072052 A034848 * A139972 A268426 A155573 Adjacent sequences:  A168107 A168108 A168109 * A168111 A168112 A168113 KEYWORD base,nonn AUTHOR Jonathan Vos Post, Nov 18 2009 EXTENSIONS Terms beyond a(10) by R. J. Mathar, Dec 06 2009 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 16 10:55 EDT 2019. Contains 328056 sequences. (Running on oeis4.)