A173596 The larger member of a near-repdigit emirp pair.

311, 733, 991, 1511, 1811, 3433, 3733, 7717, 7757, 16111, 79777, 99989, 112111, 333323, 334333, 733333, 778777, 787777, 911111, 999199, 1171111, 3733333, 9999299, 11131111, 11911111

Offset

1,1

Comments

a(n) and an associated A173595 = A004086(a(n)) (not necessarily at the same position n) are a near-repdigit emirp pair, and all these pairs, sorted, generate A173594.

Links

Table of n, a(n) for n=1..25.

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:
isA173596 := proc(n) return isA173594(n) and digrev(n) < n end proc:
for n from 2 do if isA173596(n) then printf("%d, ", n) ; fi ; end do ; # R. J. Mathar, Mar 05 2010

Crossrefs

Cf. A173594, A173595.

Sequence in context: A142576 A374103 A025024 * A067379 A067374 A055000

Adjacent sequences: A173593 A173594 A173595 * A173597 A173598 A173599

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