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.

User: Kenny Lau

Kenny Lau's wiki page.

Kenny Lau has authored 1 sequences.

A274765 Cyclops numbers with circular digits {0,6,8,9}.

Original entry on oeis.org

0, 606, 608, 609, 806, 808, 809, 906, 908, 909, 66066, 66068, 66069, 66086, 66088, 66089, 66096, 66098, 66099, 68066, 68068, 68069, 68086, 68088, 68089, 68096, 68098, 68099, 69066, 69068, 69069, 69086, 69088, 69089, 69096, 69098, 69099, 86066, 86068, 86069, 86086, 86088, 86089, 86096, 86098, 86099
Offset: 1

Author

Kenny Lau, Jul 05 2016

Keywords

Comments

Intersection of A001743 and A134808.

Examples

			86069 is a member because it is cyclops (A134808) and each digit contains at least one loop (A001743).
		

Crossrefs

Programs

  • Mathematica
    cncdQ[n_]:=Module[{idn=IntegerDigits[n]},OddQ[Length[idn]]&&Count[idn,0] == 1&&idn[[(Length[idn]+1)/2]]==0&&SubsetQ[{0,6,8,9},idn]]; Select[ Range[ 0,90000],cncdQ] (* Harvey P. Dale, Jan 06 2022 *)
  • PARI
    is_a001633(n) = #Str(n)%2==1
    is_a001743(n) = #setintersect([1, 2, 3, 4, 5, 7], Set(digits(n)))==0
    is_a134808(n) = if(n==0, return(1), if(n < 10, return(0), my(d=digits(n), x=1, y=#d); while(x < #d, if(d[x]==0, break); x++); while(y > 1, if(d[y]==0, break); y--); if(x==y && x==ceil(#Str(n)/2), return(1), return(0))))
    is(n) = is_a001633(n) && is_a001743(n) && is_a134808(n) \\ Felix Fröhlich, Jul 05 2016
  • Python
    import sys
    f = open('b274765.txt', 'w')
    i = 1
    n = 0
    a = [""]
    while True:
        for x in a:
            for y in a:
                f.write(str(i)+" "+x+"0"+y+"\n")
                i += 1
                if i>20000:
                    f.close()
                    sys.exit()
        a = sum([[x+"6", x+"8", x+"9"] for x in a], [])
    # Kenny Lau, Jul 05 2016