A162708 - OEIS

%I #5 Feb 26 2019 23:03:19

%S 10,14,16,18,19,20,21,22,24,27,28,30,33,34,36,37,38,39,40,41,42,43,44,

%T 45,46,47,48,49,50,51,52,54,66,68,69,70,72,73,74,75,76,78,79,81,82,84,

%U 85,86,87,88,89,90,92,93,94,95,96,97,98,99,100,102,103,104,105,106,107,108,109

%N Numbers that are the sum of two reversed primes in more than one way.

%C Subsequence of A162706. - _R. J. Mathar_, Jul 13 2009

%e 14 = R(7) + R(7) = R(3) + R(11).

%e 28 = R(11) + R(71) = 11 + 17 = R(41) + R(41) = 14 + 14.

%e 33 = 2 + 31 = R(2) + R(13) = 16 + 17 = R(61) + R(71).

%e 36 = R(2) + R(43) = 2 + 34 = R(5) + R(13) = 5 + 31.

%p read("transforms") ; A055642 := proc(n) max(1, ilog10(n)+1) ; end:

%p A004087 := proc(n) option remember; digrev(ithprime(n)) ; end:

%p isA162708 := proc(n) c := 0 ; for i from 1 do p := ithprime(i) ; if A055642(p) > A055642(n) then break; fi; for j from 1 to i do if A004087(i)+A004087(j) = n then c := c+1; fi; od: od: RETURN(c > 1); end:

%p for n from 1 to 200 do if isA162708(n) then printf("%d,",n) ; fi; od: # _R. J. Mathar_, Jul 13 2009

%K nonn,base

%O 1,1

%A _Claudio Meller_, Jul 11 2009

%E Missing terms 14, 33, etc. inserted by _R. J. Mathar_, Jul 13 2009