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 11 results. Next

A046501 Primes with multiplicative persistence value 1.

Original entry on oeis.org

11, 13, 17, 19, 23, 31, 41, 61, 71, 101, 103, 107, 109, 113, 131, 151, 181, 191, 211, 241, 307, 311, 313, 331, 401, 409, 421, 503, 509, 601, 607, 701, 709, 809, 811, 907, 911, 1009, 1013, 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061, 1063, 1069, 1087
Offset: 1

Views

Author

Patrick De Geest, Sep 15 1998

Keywords

Comments

The numbers < 10 have persistence 0. - T. D. Noe, Nov 23 2011
Also: Primes having either at least one digit "0", or any number of digits "1" and product of digits > 1 less than 10 (i.e., among {2, ..., 9, 2*2, 2*3, 2*4, 3*3, 2*2*2}). Terms without a digit "0" and such that deleting some digits "1" never yields an earlier term could be called "primitive". There are only finitely many such elements. If the terms < 10 are ignored, the primitive elements are 11, ..., 71, 151, 181, 211, 241, 313, 421, 811, 911, ... - M. F. Hasler, Sep 25 2012

Examples

			181 -> 1*8*1 = 8; one digit in one step.
		

Crossrefs

Intersection of A000040 and A046510.
Cf. A046500.

Programs

  • Mathematica
    Select[Prime[Range[179]], IntegerLength[Times @@ IntegerDigits[#]] <= 1 &] (* Jayanta Basu, Jun 26 2013 *)
  • PARI
    is_A046501(n)={isprime(n) || return; my(P=n%10); while(P & n\=10, (P*=n%10)>9 & return);1}  \\ M. F. Hasler, Sep 25 2012
    
  • Python
    from math import prod
    from sympy import isprime
    def ok(n): return n > 9 and prod(map(int, str(n))) < 10 and isprime(n)
    print([k for k in range(1088) if ok(k)]) # Michael S. Branicky, Mar 14 2022

Extensions

Numbers < 10 removed, as they have a multiplicative persistence of 0, by Daniel Mondot, Mar 14 2022

A046502 Primes with multiplicative persistence value 2.

Original entry on oeis.org

29, 37, 43, 53, 67, 73, 83, 127, 137, 163, 167, 173, 199, 223, 233, 251, 257, 269, 271, 281, 317, 349, 431, 439, 457, 461, 521, 523, 541, 547, 563, 569, 587, 599, 613, 617, 631, 641, 653, 659, 761, 821, 827, 853, 857, 859, 919, 991, 1129, 1153, 1163, 1217
Offset: 1

Views

Author

Patrick De Geest, Sep 15 1998

Keywords

Examples

			29 -> 2 * 9 -> [ 18 ] -> 1 * 8 -> [ 8 ] -> one digit in two steps.
		

Crossrefs

Intersection of A000040 and A046511.
Cf. A046500.

A046503 Primes with multiplicative persistence value 3.

Original entry on oeis.org

47, 59, 79, 89, 97, 139, 149, 157, 179, 193, 197, 227, 229, 239, 263, 283, 293, 337, 347, 353, 359, 367, 373, 383, 389, 419, 433, 443, 449, 463, 479, 487, 491, 499, 571, 577, 593, 619, 643, 661, 673, 683, 691, 719, 733, 743, 751, 757, 797, 823, 829, 839
Offset: 1

Views

Author

Patrick De Geest, Sep 15 1998

Keywords

Examples

			47 -> 4 * 7 -> [ 28 ] -> 2 * 8 -> [ 16 ] -> 1 * 6 -> [ 6 ] -> one digit in three steps.
		

Crossrefs

Programs

  • Maple
    filter:= proc(n) local L;
      if not isprime(n) then return false fi;
      L:= convert(convert(n,base,10),`*`); if L < 10 then return false fi;
      L:= convert(convert(L,base,10),`*`); if L < 10 then return false fi;
      L:= convert(convert(L,base,10),`*`); evalb(L < 10)
    end proc:
    select(filter, [seq(i,i=11..1000,2)]); # Robert Israel, Jun 05 2018
  • Mathematica
    pr3Q[n_] := Length[NestWhileList[Times @@ IntegerDigits[#] &, n, # > 9 &]] == 4; Select[Prime[Range[147]], pr3Q] (* Jayanta Basu, Jun 26 2013 *)

A046504 Primes with multiplicative persistence value 4.

Original entry on oeis.org

277, 379, 397, 467, 557, 647, 677, 727, 739, 773, 787, 877, 887, 937, 1277, 1483, 1489, 1553, 1699, 1747, 1777, 1783, 1787, 1867, 1873, 1877, 1973, 1999, 2267, 2347, 2377, 2399, 2437, 2467, 2473, 2477, 2647, 2683, 2687, 2689, 2699, 2797, 2837, 2861
Offset: 1

Views

Author

Patrick De Geest, Sep 15 1998

Keywords

Examples

			277 -> [ 98 ][ 72 ][ 14 ][ 4 ] -> one digit in four steps.
		

Crossrefs

Intersection of A000040 and A046513.
Cf. A046500.

Programs

  • Mathematica
    pmp4Q[n_]:=Length[NestWhileList[Times@@IntegerDigits[#]&,n,#>9&]]==5; Select[Prime[Range[500]],pmp4Q] (* Harvey P. Dale, Oct 10 2016 *)

A046505 Primes with multiplicative persistence value 5.

Original entry on oeis.org

769, 967, 1697, 2777, 3637, 3673, 4483, 6197, 6337, 6373, 6719, 6733, 6779, 6791, 6917, 6971, 6977, 7559, 7691, 7727, 8443, 8681, 8861, 9677, 9767, 12379, 12739, 12973, 13297, 13367, 13729, 13763, 14779, 14797, 14843, 17239, 17293, 17497
Offset: 1

Views

Author

Patrick De Geest, Sep 15 1998

Keywords

Examples

			769 -> [ 378 ][ 168 ][ 48 ][ 32 ][ 6 ] -> one digit in five steps.
		

Crossrefs

Intersection of A000040 and A046514.
Cf. A046500.

Programs

  • Mathematica
    mp5Q[n_]:=Length[NestWhileList[Times@@IntegerDigits[#]&,n,#>9&]]==6; Select[ Prime[Range[2100]],mp5Q] (* Harvey P. Dale, Dec 30 2019 *)

A046506 Primes with multiplicative persistence value 6.

Original entry on oeis.org

8867, 23887, 27883, 28387, 28837, 32887, 34487, 34847, 38287, 38447, 43487, 44647, 46447, 47843, 48437, 48473, 49999, 72883, 74843, 78283, 78823, 82387, 82837, 84347, 84437, 87443, 88237, 88327, 94999, 118687, 123887, 126487, 128467
Offset: 1

Views

Author

Patrick De Geest, Sep 15 1998

Keywords

Examples

			8867 -> [ 2688 ][ 768 ][ 336 ][ 54 ][ 20 ][ 0 ] -> one digit in six steps.
		

Crossrefs

Programs

  • Maple
    filter:= proc(n) local L,i;
      L:= convert(convert(n,base,10),`*`); if L < 10 then return false fi;
      for i from 2 to 5 do
         L:= convert(convert(L,base,10),`*`); if L < 10 then return false fi
        od;
      L:= convert(convert(L,base,10),`*`); evalb(L < 10)
    end proc:
    count:= 0: Res:= NULL;
    p:= 11:
    while count < 100 do
      p:= nextprime(p);
      if filter(p) then count:= count+1; Res:= Res,p fi
    od:
    Res; # Robert Israel, Jun 06 2018

Extensions

Offset corrected by Robert Israel, Jun 06 2018

A046507 Primes with multiplicative persistence value 7.

Original entry on oeis.org

186889, 188869, 246889, 248869, 264889, 269779, 279679, 279967, 284689, 288389, 288649, 288839, 296797, 297967, 376679, 376769, 377779, 379667, 379777, 426889, 444869, 467879, 467897, 468289, 468683, 469787, 469877, 478679, 478697, 478769
Offset: 1

Views

Author

Patrick De Geest, Sep 15 1998

Keywords

Examples

			186889 -> [ 27648 ][ 2688 ][ 768 ][ 336 ][ 54 ][ 20 ][ 0 ] -> one digit in seven steps.
		

Crossrefs

A046508 Primes with multiplicative persistence value 8.

Original entry on oeis.org

2678789, 2687879, 2687897, 2688797, 2688977, 2689877, 2697887, 2768789, 2768897, 2769887, 2778689, 2786789, 2787689, 2788769, 2798687, 2798867, 2868779, 2868977, 2876789, 2876879, 2878679, 2878697, 2878769, 2879687
Offset: 1

Views

Author

Patrick De Geest, Sep 15 1998

Keywords

Examples

			2678789 -> [ 338688 ][ 27648 ][ 2688 ][ 768 ][ 336 ][ 54 ][ 20 ][ 0 ] -> one digit in eight steps.
		

Crossrefs

Intersection of A000040 and A046517.
Cf. A046500.

Programs

  • Mathematica
    mp8Q[n_]:=Length[NestWhileList[Times@@IntegerDigits[#]&,n,#>9&]]==9; Select[ Prime[ Range[210000]],mp8Q] (* Harvey P. Dale, Mar 30 2019 *)

A046509 Primes with multiplicative persistence value 9.

Original entry on oeis.org

26899889, 28698899, 28699889, 28869989, 28889699, 28899869, 28989689, 29868989, 29888699, 29968889, 29988869, 38849989, 38894899, 38898949, 38899489, 38984989, 39849889, 43898989, 43988899, 43989889, 46668899
Offset: 1

Views

Author

Patrick De Geest, Sep 15 1998

Keywords

Examples

			26899889 -> [ 4478976 ][ 338688 ][ 27648 ][ 2688 ][ 768 ][ 336 ][ 54 ][ 20 ][ 0 ] -> one digit in nine steps.
		

Crossrefs

Intersection of A000040 and A046518.
Cf. A046500.

A157837 Smallest emirp with multiplicative persistence n.

Original entry on oeis.org

13, 37, 79, 739, 769, 32887, 186889, 3748879, 92888699, 3778889899, 727777887889889
Offset: 1

Views

Author

Lekraj Beedassy, Mar 07 2009

Keywords

Crossrefs

Extensions

Corrected a(11). Lekraj Beedassy, Mar 10 2009
a(8) and a(11) corrected by Ray Chandler, Mar 12 2009
Showing 1-10 of 11 results. Next