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 1-10 of 13 results. Next

A134962 Numbers n with property that for each single digit d of n, we can also see the decimal expansion of d^2 as a substring of n. Also n may not contain any 0 digits.

Original entry on oeis.org

1, 11, 111, 1111, 11111, 111111, 1111111, 3648169, 3649816, 3681649, 3698164, 8163649, 8164369, 8164936, 8169364, 9364816, 9368164, 9816364, 9816436, 11111111, 13648169, 13649816, 13681649, 13698164, 16364819, 16364981
Offset: 1

Views

Author

Zak Seidov and N. J. A. Sloane, Feb 03 2008

Keywords

Comments

The number of terms less than 10^k: 1, 2, 3, 4, 5, 6, 19, 410, 8083, ... . - Robert G. Wilson v, Jan 06 2012

Examples

			In 3648169, for 3 we can see 9, for 6 we can see 36, for 4 we can see 16, for 8 we can see 64, for 1 we can see 1 and for 9 we can see 81.
		

Crossrefs

Programs

  • Mathematica
    fQ[n_] := (id = IntegerDigits@ n; Union[id][[1]] != 0 && Sort[ StringPosition[ ToString[n], ToString[#]] & /@ Evaluate[ id^2]][[1]] != {}); k = 0; lst = {}; While[k < 2*10^7, If[fQ@k, AppendTo[lst, k]; Print@ k]; k++] (* Robert G. Wilson v, Jan 06 2012 *)
  • Python
    sq = {d:str(int(d)**2) for d in "123456789"}
    def ok(n): return "0" not in (s:=str(n)) and all(sq[d] in s for d in set(s))
    print([k for k in range(10**7) if ok(k)]) # Michael S. Branicky, May 05 2023

Extensions

a(9) onwards computed by David Applegate, Feb 03 2008

A134692 Numbers k with the property that for each digit d from 1 to 9, the decimal expansion of d^3 is a substring of k.

Original entry on oeis.org

1251216427293438, 1251216427298343, 1251216434327298, 1251216434382729, 1251216482729343, 1251216483432729, 1251272921643438, 1251272921648343, 1251272934321648, 1251272934382164, 1251272982164343, 1251272983432164
Offset: 1

Views

Author

Zak Seidov, Feb 02 2008

Keywords

Comments

See A134439 for further information.

Crossrefs

Extensions

Corrected by David Applegate, Feb 09 2008

A134439 Numbers n with property that for each digit d from 1 to 9, we can also see the decimal expansion of d^2 as a substring of n.

Original entry on oeis.org

2536497816, 2536498167, 2536781649, 2536816497, 2573649816, 2573681649, 2578163649, 2578164936, 2581636497, 2581649367, 2581649736, 2581673649, 3625781649, 3625816497, 3649257816, 3649258167, 3649725816, 3649781625
Offset: 1

Views

Author

Zak Seidov, Feb 02 2008

Keywords

Examples

			In the first number, for 2 we can see 4, for 5 we can see 25, for 3 we can see 9, for 6 we can see 36, for 4 we can see 16, for 9 we can see 81, for 8 we can see 64, for 1 we can see 1 and for 7 we can see 49.
		

Crossrefs

Extensions

Corrected by David Applegate, Feb 09 2008

A050741 Numbers k such that the decimal expansion of k^2 contains no pair of consecutive equal digits.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 14, 16, 17, 18, 19, 22, 23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 36, 37, 39, 41, 42, 43, 44, 45, 48, 49, 51, 52, 53, 54, 55, 56, 57, 59, 61, 63, 64, 66, 68, 69, 71, 72, 73, 74, 75, 77, 78, 79, 81, 82, 84, 86, 87, 89, 91, 92, 93, 95, 96, 97
Offset: 1

Views

Author

Patrick De Geest, Sep 15 1999

Keywords

Examples

			10 is absent because 10^2=100 with repeating 0,
12 is absent because 12^2=144 with repeating 4,
21 is absent because 21^2=441 with repeating 4.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[0,97],FreeQ[Differences[IntegerDigits[#^2]],0]&] (* Jayanta Basu, May 31 2013 *)

Extensions

Edited by N. J. A. Sloane, Mar 16 2008

A134948 Self-factorial numbers: numbers n with property that for each single digit d of n, we can also see the decimal expansion of d! as a substring of n.

Original entry on oeis.org

1, 2, 10, 11, 12, 21, 22, 24, 100, 101, 102, 110, 111, 112, 120, 121, 122, 124, 201, 210, 211, 212, 221, 222, 224, 241, 242, 244, 424, 1000, 1001, 1002, 1010, 1011, 1012, 1020, 1021, 1022, 1024, 1100, 1101, 1102, 1110, 1111, 1112, 1120, 1121, 1122, 1124, 1200
Offset: 1

Views

Author

Keywords

Comments

As 9 does not occur in d! for all d in {0..9}, all self-factorials cannot contain 9 as a digit, cf. A007095. - Reinhard Zumkeller, Sep 26 2014

Examples

			24 is a self-factorial number because we can see both 2! = 2 and 4! = 24 in the decimal expansion 24.
		

Crossrefs

Programs

  • Haskell
    import Data.List (nub, sort, isInfixOf)
    a134948 n = a134948_list !! (n-1)
    a134948_list = filter h [0..] where
       h x = all (`isInfixOf` xs)
                 (map (fss !!) $ map (read . return) $ sort $ nub xs)
             where xs = show x
       fss = map show $ take 10 a000142_list
    -- Reinhard Zumkeller, Sep 26 2014
  • Maple
    isA134948 := proc(n) local nbase10,dgs,d,dfac ; nbase10 := convert(n,base,10) ; dgs := convert(nbase10,set) ; for d in dgs do dfac := convert(d!,base,10) ; if verify(dfac,nbase10,'sublist') = false then RETURN(false) ; fi ; od: RETURN(true) ; end: for n from 1 to 10000 do if isA134948(n) then printf("%d ",n) ; fi ; od: # R. J. Mathar, Feb 05 2008

Extensions

a(1) - a(18) computed by N. J. A. Sloane, Feb 02 2008
a(19) onwards from David Applegate, Feb 09 2008
More terms from R. J. Mathar, Feb 05 2008

A135015 Numbers n with property that for each single digit d of n, we can also see the decimal expansion of the d-th prime as a substring of n. Also n may not contain any zero digits.

Original entry on oeis.org

11235, 11253, 11325, 11352, 11523, 11532, 21135, 21153, 23115, 23511, 25113, 25311, 31125, 31152, 32115, 32511, 35112, 35211, 51123, 51132, 52113, 52311, 53112, 53211, 111235, 111253, 111325, 111352, 111523, 111532, 112135, 112153, 112235, 112253
Offset: 1

Views

Author

David Applegate and N. J. A. Sloane, Feb 10 2008

Keywords

Crossrefs

Programs

  • Maple
    filter:= proc (n) local L, LP;
      L := convert(n, base, 10);
      if has(L, 0) then return false end if;
    if has(L, 1) and not has(L, 2) then return false end if;
    if has(L, 2) and not has(L, 3) then return false end if;
    if has(L, 3) and not has(L, 5) then return false end if;
    if has(L, 4) and not has(L, 7) then return false end if;
    LP := [seq([L[i], L[i+1]], i = 1 .. nops(L)-1)];
    if has(L, 5) and not member([1, 1], LP) then return false end if;
    if has(L, 6) and not member([3, 1], LP) then return false end if;
    if has(L, 7) and not member([7, 1], LP) then return false end if;
    if has(L, 8) and not member([9, 1], LP) then return false end if;
    if has(L, 9) and not member([3, 2], LP) then return false end if;
    true
    end proc:
    select(filter, [$1..1.5*10^5]);

A135016 Numbers n with property that for each single digit d of n, we can also see the decimal expansion of 2^d as a substring of n. Also n may not contain any zero digits.

Original entry on oeis.org

1642, 2164, 11642, 12164, 16264, 16412, 16421, 16422, 16424, 16426, 16442, 16462, 16642, 21164, 21641, 21642, 21644, 21646, 21664, 22164, 24164, 26164, 26416, 41642, 42164, 61642, 62164, 64162, 64216, 111642, 112164, 116264, 116412, 116421, 116422
Offset: 1

Views

Author

David Applegate and N. J. A. Sloane, Feb 10 2008

Keywords

Crossrefs

A135464 Numbers n with property that for each single digit d of the base 3 expansion of n, we can also see the base 3 expansion of d^2 as a substring. Also n may not contain any 0 digits.

Original entry on oeis.org

1, 11, 111, 112, 211, 1111, 1112, 1121, 1122, 1211, 2111, 2112, 2211, 11111, 11112, 11121, 11122, 11211, 11212, 11221, 11222, 12111, 12112, 12211, 21111, 21112, 21121, 21122, 21211, 22111, 22112, 22211, 111111, 111112, 111121
Offset: 1

Views

Author

David Applegate and N. J. A. Sloane, Feb 07 2008

Keywords

Comments

The base 3 expansion of n may only contain 1's and 2's and if a 2 is present then 11 must also be present. These are the only restrictions.

Crossrefs

Base-3 analog of A134962. Cf. A135465.

Programs

  • AWK
    awk 'function g(s,v,n){if (n==0){if (index(s,"2")==0||index(s,"11")>0)print v;}else{g(s "1",v*3+1,n-1); g(s "2",v*3+2,n-1);}}BEGIN{for (i=1; i<=8; i++)g("",0,i);}' # David Applegate
    (C++) // See the Applegate link in A135463.

A135465 Decimal equivalents of A135465.

Original entry on oeis.org

1, 4, 13, 14, 22, 40, 41, 43, 44, 49, 67, 68, 76, 121, 122, 124, 125, 130, 131, 133, 134, 148, 149, 157, 202, 203, 205, 206, 211, 229, 230, 238, 364, 365, 367, 368, 373, 374, 376, 377, 391, 392, 394, 395, 400, 401, 403, 404, 445, 446, 448, 449
Offset: 1

Views

Author

David Applegate and N. J. A. Sloane, Feb 07 2008

Keywords

A135495 Numbers n with property that for each single digit d of n, we can also see the decimal expansion of 2d as a substring of n.

Original entry on oeis.org

0, 121648, 121684, 124168, 124816, 128164, 128416, 161248, 161284, 164128, 164812, 168124, 168412, 412168, 412816, 416128, 416812, 481216, 481612, 812164, 812416, 816124, 816412, 841216, 841612, 1121648, 1121684, 1124168
Offset: 1

Views

Author

Zak Seidov, Feb 08 2008

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[0, 10^6], Function[d, AllTrue[IntegerDigits[2 d], SequenceCount[d, #] >= 1 &]]@ IntegerDigits[#] &] (* Michael De Vlieger, Jan 11 2018 *)

Extensions

Corrected by David Applegate, Feb 09 2008
Showing 1-10 of 13 results. Next