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The smaller member of a near-repdigit emirp pair.
3

%I #5 Jan 27 2019 20:29:27

%S 113,199,337,1151,1181,3343,3373,7177,7577,11161,77797,98999,111119,

%T 111211,323333,333337,333433,777787,777877,991999,1111711,3333373,

%U 9929999,11111117,11111911,11113111

%N The smaller member of a near-repdigit emirp pair.

%C a(n) and an associated A173596 = A004086(a(n)) are a near-repdigit emirp pair, and all these pairs united, sorted, generate A173594.

%e a(3) = 337 and A173596(2) = 733 are an emirp pair using only two different digits.

%p read("transforms") ; isA164937 := proc(n) local dse ; if isprime(n) and n > 100 then dse := convert(convert(n,base,10),multiset) ; if nops(dse) = 2 then op(2,op(1,dse)) = 1 and op(2,op(2,dse)) > 1 or op(2,op(1,dse)) > 1 and op(2,op(2,dse)) = 1; else false; end if ; else false; end if; end proc:

%p isA006567 := proc(n) if isprime(n) then pr := digrev(n) ; return isprime(pr) and pr <> n ; else false; end if; end proc:

%p isA173594 := proc(n) isA164937(n) and isA006567(n) ; end proc:

%p isA173595 := proc(n) return isA173594(n) and digrev(n) > n end proc:

%p for n from 2 do if isA173595(n) then printf("%d,",n) ; fi ; end do ; # _R. J. Mathar_, Mar 05 2010

%Y Cf. A173594, A173596.

%K base,nonn

%O 1,1

%A _Lekraj Beedassy_, Feb 22 2010

%E Keyword:base added by _R. J. Mathar_, Feb 24 2010, Mar 05 2010