cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

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

Original entry on oeis.org

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

Views

Author

Lekraj Beedassy, Feb 22 2010

Keywords

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.

Crossrefs

Programs

  • 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

Extensions

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

A210547 Lesser of emirp pairs whose members have prime digital products.

Original entry on oeis.org

13, 17, 113, 1151, 111211, 1111711, 11111117, 11113111, 111111131, 1111115111, 11111111113, 111111111111111131, 1111111111111111111111111511, 11111111111111111711111111111, 111111111111111111111111111111111111131
Offset: 1

Views

Author

Lekraj Beedassy, Mar 22 2012

Keywords

Comments

Beyond the first two terms, a(n) is the intersection of A173595 and A046703.

Crossrefs

Extensions

More terms from Alois P. Heinz, Mar 22 2012

A173594 Near-repdigit emirps.

Original entry on oeis.org

113, 199, 311, 337, 733, 991, 1151, 1181, 1511, 1811, 3343, 3373, 3433, 3733, 7177, 7577, 7717, 7757, 11161, 16111, 77797, 79777, 98999, 99989, 111119, 111211, 112111, 323333, 333323, 333337, 333433, 334333, 733333, 777787, 777877, 778777, 787777, 911111
Offset: 1

Views

Author

Lekraj Beedassy, Feb 22 2010

Keywords

Comments

Entries of A164937 that are emirps (A006567), i.e., A164937 INTERSECTION A006567.

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[26,75000]],!PalindromeQ[#]&&PrimeQ[IntegerReverse[ #]] && Count[ DigitCount[#],0]==8&&MemberQ[DigitCount[#],1]&] (* Harvey P. Dale, Sep 17 2021 *)
Showing 1-3 of 3 results.