A173595 The smaller member of a near-repdigit emirp pair.

113, 199, 337, 1151, 1181, 3343, 3373, 7177, 7577, 11161, 77797, 98999, 111119, 111211, 323333, 333337, 333433, 777787, 777877, 991999, 1111711, 3333373, 9929999, 11111117, 11111911, 11113111

Offset

1,1

Comments

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

Links

Table of n, a(n) for n=1..26.

Example

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

Maple

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:
isA006567 := proc(n) if isprime(n) then pr := digrev(n) ; return isprime(pr) and pr <> n ; else false; end if; end proc:
isA173594 := proc(n) isA164937(n) and isA006567(n) ; end proc:
isA173595 := proc(n) return isA173594(n) and digrev(n) > n end proc:
for n from 2 do if isA173595(n) then printf("%d, ", n) ; fi ; end do ; # R. J. Mathar, Mar 05 2010

Crossrefs

Cf. A173594, A173596.

Sequence in context: A173594 A074982 A094932 * A142276 A054695 A054696

Adjacent sequences: A173592 A173593 A173594 * A173596 A173597 A173598

Keyword

base,nonn

Author

Lekraj Beedassy, Feb 22 2010

Extensions

Keyword:base added by R. J. Mathar, Feb 24 2010, Mar 05 2010

Status

approved