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 1-4 of 4 results.

A038808 Palindromic numbers which are the difference of two positive cubes.

Original entry on oeis.org

0, 7, 919, 999, 25352, 27872, 31213, 37973, 45054, 53135, 54845, 56765, 60606, 62426, 63936, 74347, 75357, 78687, 86868, 90909, 98289, 121121, 757757, 982289, 999999, 1063601, 1081801, 1188811, 1197911, 1366631, 1393931, 1507051, 1644461, 1727271, 1889881
Offset: 1

Views

Author

Jeff Burch

Keywords

Links

Crossrefs

Cf. A002113, A038593, A109879.

Programs

  • Mathematica
    NextPalindrome[n_] := Block[ {l = Floor[ Log[10, n] + 1], idn = IntegerDigits[n]}, If[ Union[ idn] == {9}, Return[n + 2], If[l < 2, Return[n + 1], If[ FromDigits[ Reverse[ Take[ idn, Ceiling[l/2]]]] > FromDigits[ Take[ idn, -Ceiling[l/2]]], FromDigits[ Join[ Take[ idn, Ceiling[l/2]], Reverse[ Take[ idn, Floor[l/2]]]]], idfhn = FromDigits[ Take[ idn, Ceiling[l/2]]] + 1; idp = FromDigits[ Join[ IntegerDigits[ idfhn], Drop[ Reverse[ IntegerDigits[ idfhn]], Mod[l, 2]]]]]]]]; t1 = NestList[ NextPalindrome, 0, 2800]; t2 = Select[ Union[Flatten[Table[n^3 - m^3, {n, 900}, {m, n - 1}]]], # < 2*10^6 &]; Intersection[t1, t2] (* Robert G. Wilson v, Jul 14 2005 *)

Extensions

More terms from Robert G. Wilson v, Jul 14 2005

A109880 Numbers k such that k and its digit reversal both are difference of successive cubes.

Original entry on oeis.org

1, 7, 19, 91, 127, 721, 919, 14491, 19441, 113491, 177877, 194311, 778771, 1081801, 1188811, 1767169, 1927207, 1946491, 7027291, 9617671, 16056847, 74775169, 74865061, 96157747, 129869461, 164968921, 167828761, 180676081, 189202267, 757333297, 762202981, 792333757, 1917766117, 7116677191
Offset: 1

Views

Author

Amarnath Murthy, Jul 10 2005

Keywords

Comments

A subsequence of A109879.

Examples

			19 = 3^3-2^3 and 91 = 6^3-5^3.

Crossrefs

Cf. A109879.

Programs

  • Mathematica
    okQ[x_]:=Module[{revx=FromDigits[Reverse[IntegerDigits[x]]]},And@@(And@@IntegerQ/@(n/.Solve[1+3n+3n^2==x,n])&&And@@IntegerQ/@(n/.Solve[1+3n+3n^2==revx,n]))]; Select[Range[20000], okQ] (* Harvey P. Dale, Aug 06 2007 *)

Extensions

More terms from Harvey P. Dale, Aug 06 2007
23 more terms from Donovan Johnson, Feb 21 2008

A104339 Numbers n such that n and its digit reversal both are difference of (positive or negative) cubes.

Original entry on oeis.org

0, 1, 2, 7, 8, 9, 16, 19, 27, 56, 61, 65, 72, 91, 127, 133, 215, 243, 331, 342, 343, 397, 512, 657, 686, 721, 737, 756, 793, 919, 999, 1001, 1008, 1331, 1332, 1339, 1385, 1727, 2232, 2322, 2331, 2662, 2744, 3159, 4069, 4097, 4376, 4472, 4608, 5409, 5707, 5831
Offset: 1

Views

Author

Robert G. Wilson v, Jul 16 2005

Keywords

Crossrefs

Cf. A109879.

Programs

  • Mathematica
    t1 = Select[ Union[ Flatten[ Table[n^3 - m^3, {n, 35}, {m, -35, n - 1}]]], # < 10^4 && Mod[ #, 10] != 0 &]; t2 = FromDigits /@ Reverse /@ IntegerDigits /@ t1; Take[ Intersection[t1, t2], 51]

A110222 Palindromic numbers which are not the absolute difference of a cube and a square.

Original entry on oeis.org

6, 66, 77, 88, 111, 181, 202, 363, 383, 434, 454, 474, 494, 555, 565, 595, 606, 646, 666, 707, 717, 747, 787, 818, 838, 858, 929, 949, 959, 979, 989, 1221, 1551, 1661, 2002, 2442, 2662, 3003, 3443, 3773, 3883, 4114, 4334, 4444, 4774, 4884, 5005, 5115, 5335
Offset: 1

Views

Author

Robert G. Wilson v, Jul 16 2005

Keywords

Comments

The palindromes in A110223.

Crossrefs

Cf. A109879, A074981, A110223.

Programs

  • Mathematica
    NextPalindrome[n_] := Block[ {l = Floor[ Log[10, n] + 1], idn = IntegerDigits[n]}, If[ Union[ idn] == {9}, Return[n + 2], If[l < 2, Return[n + 1], If[ FromDigits[ Reverse[ Take[ idn, Ceiling[l/2]]]] > FromDigits[ Take[ idn, -Ceiling[l/2]]], FromDigits[ Join[ Take[ idn, Ceiling[l/2]], Reverse[ Take[ idn, Floor[l/2]]]]], idfhn = FromDigits[ Take[ idn, Ceiling[l/2]]] + 1; idp = FromDigits[ Join[ IntegerDigits[ idfhn], Drop[ Reverse[ IntegerDigits[ idfhn]], Mod[l, 2]]]]]]]]; t1 = NestList[ NextPalindrome, 0, 130]; t2 = Union[ Flatten[ Table[ Select[ Table[ Abs[n^3 - m^2], {m, 0, 10000}], # < 10^3 &], {n, -5000, 5000}]]]; Take[ Complement[t1, Intersection[t1, t2]], 50]
Showing 1-4 of 4 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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