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.

A230083 Smaller of two consecutive primes whose product of digits is equal and nonzero.

Original entry on oeis.org

1913, 2819, 6719, 14519, 16319, 18379, 19319, 21419, 29819, 34613, 35617, 35879, 36979, 37379, 37619, 37813, 39119, 45613, 46619, 46919, 49279, 51613, 55313, 56179, 56713, 58613, 62219, 63179, 65479, 66413, 74779, 75913, 76213, 76579, 76679, 79319, 82619
Offset: 1

Views

Author

Shyam Sunder Gupta, Oct 08 2013

Keywords

Examples

			1913 is in the sequence because 1913 and 1931 are consecutive primes and the product of the digits of each = 27.

Links

Crossrefs

Cf. A230082, A007954, A053666.

Programs

  • Mathematica
    a = {}; m = 1; s = 1; Do[If[(y = Apply[Times, IntegerDigits[x = Prime[n]]]) == s && s != 0, m = m + 1; If[m > 1, AppendTo[a, Prime[n - 1]]], m = 1]; s = y, {n, 1, 10000}]; a

A230084 Smallest of three consecutive primes whose product of digits is equal and nonzero.

Original entry on oeis.org

442619, 2483219, 6325619, 7567919, 7886519, 9883673, 9962219, 11117123, 14669519, 15446819, 17958419, 21337279, 23623129, 26453671, 26872919, 27234419, 27536519, 27948343, 32638213, 32964341, 33539783, 33813419, 34277819, 34554719, 35732381, 37571519
Offset: 1

Views

Author

Shyam Sunder Gupta, Oct 08 2013

Keywords

Examples

			442619 is in the sequence because 442619,442633 and 442691 are consecutive primes and the product of the digits of each = 1728.

Links

Crossrefs

Cf. A230082, A230083, A007954, A053666.

Programs

  • Mathematica
    a = {}; m = 1; s = 1; Do[ If[(y = Apply[Times, IntegerDigits[x = Prime[n]]]) == s && s != 0, m = m + 1; If[m > 2, AppendTo[a, Prime[n - 2]]], m = 1]; s = y, {n, 1, 100000}]; a
Transpose[Select[Partition[Prime[Range[23*10^5]],3,1],Times@@ IntegerDigits[ #[[1]]]==Times@@IntegerDigits[#[[2]]] == Times@@ IntegerDigits[#[[3]]]>0&]][[1]] (* Harvey P. Dale, Apr 05 2016 *)
pdeQ[{a_,b_,c_}]:=Module[{un=Union[Times@@@IntegerDigits[{a,b,c}]]},un != {0} && Length[un]==1]; Select[Partition[Prime[Range[23*10^5]],3,1],pdeQ][[All,1]] (* Harvey P. Dale, Feb 01 2022 *)

A230228 a(n) is the smallest palindromic prime that is the first of n consecutive palindromic primes whose product of digits is equal and nonzero.

Original entry on oeis.org

2, 191, 1123529253211, 3868168229228618683, 164471141292141174461
Offset: 1

Views

Author

Shyam Sunder Gupta, Oct 12 2013

Keywords

Comments

a(6) > 10^22.

Examples

			a(2) = 191, since 191 and 313 are two consecutive palindromic primes with product of digits as 9 and this is the first occurrence of two consecutive palindromic primes whose product of digits is equal and nonzero.

Crossrefs

Cf. A002385, A007954, A053666, A230200, A230082.

A230085 Smallest of four consecutive primes whose product of digits is equal and nonzero.

Original entry on oeis.org

336737123, 812444239, 1731191219, 2187575239, 2549315123, 2672459219, 2721498343, 2778476123, 2781452239, 2924114819, 2925926819, 3232115219, 3441686219, 3579455219, 3617846123, 3755345219, 3943951637
Offset: 1

Views

Author

Shyam Sunder Gupta, Oct 08 2013

Keywords

Examples

			336737123 is in the sequence because 336737123, 336737161, 336737213 and 336737231 are consecutive primes and the product of the digits of each = 47628.

Crossrefs

Cf. A230082, A230083, A230084, A007954, A053666.

Programs

  • Mathematica
    a = {}; m = 1; s = 1; Do[If[(y = Apply[Times, IntegerDigits[x = Prime[n]]]) == s  && s != 0,  m = m + 1; If[m > 3, AppendTo[a, Prime[n - 3]]], m = 1]; s = y, {n, 1, 200000000}]; a
pdeQ[{a_,b_,c_,d_}]:=Module[{u=Union[Times@@@(IntegerDigits/@{a,b,c,d})]}, Length[ u] ==1&&u[[1]]>0]; Transpose[Select[Partition[Prime[Range[ 19*10^7]],4,1],pdeQ]][[1]] (* Harvey P. Dale, Jan 27 2015 *)
Showing 1-4 of 4 results.

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