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.

Previous Showing 11-20 of 41 results. Next

A083185 Palindromic primes using only nonprime digits (0,1,4,6,8,9).

Original entry on oeis.org

11, 101, 181, 191, 919, 10601, 11411, 16061, 16661, 18181, 18481, 19891, 19991, 91019, 94049, 94649, 94849, 94949, 96469, 98689, 1008001, 1114111, 1160611, 1180811, 1186811, 1190911, 1196911, 1409041, 1411141, 1444441, 1461641
Offset: 1

Views

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Apr 26 2003

Keywords

Crossrefs

Palindromes in A034844.

Programs

  • Mathematica
    Select[ Prime[ Range[111500]], IntegerDigits[ # ] == Reverse[ IntegerDigits[ # ]] && Union[ Join[ IntegerDigits[ # ], {0, 1, 4, 6, 8, 9}]] == {0, 1, 4, 6, 8, 9} & ]
    Select[Prime[Range[120000]],PalindromeQ[#]&&NoneTrue[IntegerDigits[#], PrimeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 08 2018 *)

Extensions

Edited and extended by Patrick De Geest, Jun 11 2003

A092624 Numbers with exactly two prime digits.

Original entry on oeis.org

22, 23, 25, 27, 32, 33, 35, 37, 52, 53, 55, 57, 72, 73, 75, 77, 122, 123, 125, 127, 132, 133, 135, 137, 152, 153, 155, 157, 172, 173, 175, 177, 202, 203, 205, 207, 212, 213, 215, 217, 220, 221, 224, 226, 228, 229, 230, 231, 234, 236, 238, 239, 242, 243, 245
Offset: 1

Views

Author

Jani Melik, Apr 11 2004

Keywords

Comments

A193238(a(n))=2; subsequence of A118950. [Reinhard Zumkeller, Jul 19 2011]

Examples

			25 has two prime digits, 2 and 5;
207 has two prime digits, 2 and 7.
		

Crossrefs

Programs

  • Haskell
    import Data.List (elemIndices)
    a092624 n = a092624_list !! (n-1)
    a092624_list = elemIndices 2 a193238_list
    -- Reinhard Zumkeller, Jul 19 2011
  • Maple
    stev_sez:=proc(n) local i, tren, st, ans, anstren; ans:=[ ]: anstren:=[ ]: tren:=n: for i while (tren>0) do st:=round( 10*frac(tren/10) ): ans:=[ op(ans), st ]: tren:=trunc(tren/10): end do; for i from nops(ans) to 1 by -1 do anstren:=[ op(anstren), op(i,ans) ]; od; RETURN(anstren); end: ts_stpf:=proc(n) local i, stpf, ans; ans:=stev_sez(n): stpf:=0: for i from 1 to nops(ans) do if (isprime(op(i,ans))='true') then stpf:=stpf+1; # number of prime digits fi od; RETURN(stpf) end: ts_pr_nd:=proc(n) local i, stpf, ans, ans1, tren; ans:=[ ]: stpf:=0: tren:=1: for i from 1 to n do if ( ts_stpf(i) = 2) then ans:=[ op(ans), i ]: tren:=tren+1; fi od; RETURN(ans) end: ts_pr_nd(500);
  • Mathematica
    Select[Range[300],Count[IntegerDigits[#],?PrimeQ]==2&] (* _Harvey P. Dale, Apr 20 2025 *)

A092625 Numbers with exactly three prime digits.

Original entry on oeis.org

222, 223, 225, 227, 232, 233, 235, 237, 252, 253, 255, 257, 272, 273, 275, 277, 322, 323, 325, 327, 332, 333, 335, 337, 352, 353, 355, 357, 372, 373, 375, 377, 522, 523, 525, 527, 532, 533, 535, 537, 552, 553, 555, 557, 572, 573, 575, 577, 722, 723, 725
Offset: 1

Views

Author

Jani Melik, Apr 11 2004

Keywords

Comments

It is the same as A046034 from two digit numbers from 22 up to four digit numbers from 1222.
A193238(a(n))=3; subsequence of A118950. [Reinhard Zumkeller, Jul 19 2011]

Examples

			222 has three prime digits, three times 2;
1235 has three prime digits, 2, 3 and 5.
		

Crossrefs

Programs

  • Haskell
    import Data.List (elemIndices)
    a092625 n = a092625_list !! (n-1)
    a092625_list = elemIndices 3 a193238_list
    -- Reinhard Zumkeller, Jul 19 2011
  • Maple
    stev_sez:=proc(n) local i, tren, st, ans, anstren; ans:=[ ]: anstren:=[ ]: tren:=n: for i while (tren>0) do st:=round( 10*frac(tren/10) ): ans:=[ op(ans), st ]: tren:=trunc(tren/10): end do; for i from nops(ans) to 1 by -1 do anstren:=[ op(anstren), op(i,ans) ]; od; RETURN(anstren); end: ts_stpf:=proc(n) local i, stpf, ans; ans:=stev_sez(n): stpf:=0: for i from 1 to nops(ans) do if (isprime(op(i,ans))='true') then stpf:=stpf+1; # number of prime digits fi od; RETURN(stpf) end: ts_pr_nt:=proc(n) local i, stpf, ans, ans1, tren; ans:=[ ]: stpf:=0: tren:=1: for i from 1 to n do if ( ts_stpf(i) = 3) then ans:=[ op(ans), i ]: tren:=tren+1; fi od; RETURN(ans) end: ts_pr_nt(2000);
  • Mathematica
    Select[Range[800],Total[Boole[PrimeQ[IntegerDigits[#]]]]==3&] (* Harvey P. Dale, Dec 31 2023 *)

A152312 Primes without odd prime digits.

Original entry on oeis.org

2, 11, 19, 29, 41, 61, 89, 101, 109, 149, 181, 191, 199, 211, 229, 241, 269, 281, 401, 409, 419, 421, 449, 461, 491, 499, 601, 619, 641, 661, 691, 809, 811, 821, 829, 881, 911, 919, 929, 941, 991, 1009, 1019, 1021, 1049, 1061
Offset: 1

Views

Author

Omar E. Pol, Dec 02 2008

Keywords

Crossrefs

A179335 a(n) is the smallest prime which appears as a substring of the decimal representation of prime(n).

Original entry on oeis.org

2, 3, 5, 7, 11, 3, 7, 19, 2, 2, 3, 3, 41, 3, 7, 3, 5, 61, 7, 7, 3, 7, 3, 89, 7, 101, 3, 7, 109, 3, 2, 3, 3, 3, 149, 5, 5, 3, 7, 3, 7, 181, 19, 3, 7, 19, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 401, 409, 19, 2, 3, 3, 3, 3, 449, 5, 61, 3, 7, 7, 7
Offset: 1

Views

Author

Reinhard Zumkeller, Jul 11 2010

Keywords

Comments

a(n) < 10 iff prime(n) is in A179336;
a(n) = prime(n) iff prime(n) is in A033274. [Corrected by M. F. Hasler, Aug 27 2012]

Crossrefs

Programs

  • PARI
    A179335(n)={my(p=prime(n),m=0,M); for(d=1,n, M=10^d; n=p; until(n<=M || !n\=10, isprime(n%M) & (!m || m>n%M) & m=n%M); m & return(m))} \\ M. F. Hasler, Aug 27 2012
    
  • Python
    from sympy import isprime, prime
    def a(n):
        s = str(prime(n))
        ss = set(int(s[i:i+1+l]) for i in range(len(s)) for l in range(len(s)))
        return min(t for t in ss if isprime(t))
    print([a(n) for n in range(1, 94)]) # Michael S. Branicky, Jun 29 2022

A155024 Primes with distinct nonprime digits.

Original entry on oeis.org

19, 41, 61, 89, 109, 149, 401, 409, 419, 461, 491, 601, 619, 641, 691, 809, 941, 1049, 1069, 1409, 1489, 1609, 4019, 4091, 4691, 4801, 4861, 6089, 6091, 6481, 6491, 6841, 8069, 8419, 8461, 8609, 8641, 8941, 9041, 9461, 9601, 14869, 18049, 40169, 40189
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jan 19 2009

Keywords

Comments

Nonprime digits = 0, 1, 4, 6, 8 and 9.
There are only 153 terms in this sequence, all of which are in the linked b-file. - Harvey P. Dale, Dec 30 2012

Crossrefs

Cf. A029743, A034844. - R. J. Mathar, Mar 29 2010

Programs

  • Mathematica
    Select[Prime[Range[5000]],Union[PrimeQ[IntegerDigits[#]]] == {False} && Max[ DigitCount[#]]==1&] (* Harvey P. Dale, Dec 30 2012 *)
  • PARI
    is(k) = isprime(k) && setintersect([0, 1, 4, 6, 8, 9], v=vecsort(digits(k))) == v; \\ Jinyuan Wang, Mar 27 2020

Extensions

Entries checked by R. J. Mathar, Mar 29 2010

A179922 Primes with twelve embedded primes.

Original entry on oeis.org

113171, 113173, 113797, 123719, 153137, 179719, 199739, 213173, 229373, 231197, 233113, 233713, 236779, 237331, 237619, 237971, 241973, 259397, 317971, 327193, 343373, 353173, 361373, 372719, 373379, 382373, 432713, 519733, 521137, 521317
Offset: 1

Views

Author

Robert G. Wilson v, Aug 01 2010

Keywords

Comments

A079066(a(n)) = 12.

Crossrefs

Programs

  • Haskell
    import Data.List (elemIndices)
    a179922 n = a179922_list !! (n-1)
    a179922_list = map (a000040 . (+ 1)) $ elemIndices 12 a079066_list
    -- Reinhard Zumkeller, Jul 19 2011
  • Mathematica
    f[n_] := Block[ {id = IntegerDigits@n}, len = Length@ id - 1; Count[ PrimeQ@ Union[ FromDigits@# & /@ Flatten[ Table[ Partition[ id, k, 1], {k, len}], 1]], True] + 1]; Select[ Prime@ Range@ 43150, f@# == 13 &]

A152426 Primes that have both prime digits (2,3,5,7) and nonprime digits (0,1,4,6,8,9).

Original entry on oeis.org

13, 17, 29, 31, 43, 47, 59, 67, 71, 79, 83, 97, 103, 107, 113, 127, 131, 137, 139, 151, 157, 163, 167, 173, 179, 193, 197, 211, 229, 239, 241, 251, 263, 269, 271, 281, 283, 293, 307, 311, 313, 317, 331, 347, 349, 359, 367, 379
Offset: 1

Views

Author

Omar E. Pol, Dec 03 2008

Keywords

Comments

See also A152427, a subsequence without zeros.

Crossrefs

Programs

  • Mathematica
    okQ[n_] := Module[{d=Union[IntegerDigits[n]]}, Length[Intersection[d, {2,3,5,7}]]>0 && Length[Intersection[d, {0,1,4,6,8,9}]]>0]; Select[Prime[Range[100]], okQ] (* T. D. Noe, Jan 20 2011 *)

Extensions

Edited by Omar E. Pol, Jul 04 2009, Jan 20 2011
Definition clarified by N. J. A. Sloane, Jul 05 2009

A152427 Primes that have both prime digits (2,3,5,7) and nonprime digits (1,4,6,8,9).

Original entry on oeis.org

13, 17, 29, 31, 43, 47, 59, 67, 71, 79, 83, 97, 103, 107, 113, 127, 131, 137, 139, 151, 157, 163, 167, 173, 179, 193, 197, 211, 229, 239, 241, 251, 263, 269, 271, 281, 283, 293, 311, 313, 317, 331, 347, 349, 359, 367, 379, 383, 389, 397, 421, 431, 433, 439
Offset: 1

Views

Author

Omar E. Pol, Dec 03 2008

Keywords

Comments

Crossrefs

Programs

  • Mathematica
    okQ[n_] := Module[{d = Union[IntegerDigits[n]]}, Length[Intersection[d, {2, 3, 5, 7}]] > 0 && Length[Intersection[d, {1, 4, 6, 8, 9}]] > 0]; Select[Prime[Range[100]], okQ] (* T. D. Noe, Jan 21 2011 *)
    pdQ[n_]:=Module[{idn=Select[IntegerDigits[n],#!=0&]},Count[idn,?PrimeQ]>0&&Count[idn,?(!PrimeQ[#]&)]>0]; Select[Prime[Range[100]],pdQ] (* Harvey P. Dale, Jan 31 2013 *)

Formula

a(n) ~ n log n

Extensions

Corrected and extended by Harvey P. Dale, Jan 31 2013

A179910 Primes with two embedded primes.

Original entry on oeis.org

23, 37, 53, 73, 127, 139, 157, 167, 193, 211, 227, 229, 241, 251, 263, 277, 307, 331, 383, 389, 419, 433, 439, 443, 457, 467, 503, 521, 541, 557, 563, 577, 587, 599, 619, 631, 643, 647, 659, 677, 683, 727, 751, 757, 761, 827, 829, 839, 857, 859, 883, 929
Offset: 1

Views

Author

Robert G. Wilson v, Aug 01 2010

Keywords

Comments

It appears that p having n embedded primes means that the set of prime integers generated by contiguous proper substrings of p has size n.
A079066(a(n)) = 2.

Crossrefs

Programs

  • Haskell
    import Data.List (elemIndices)
    a179910 n = a179910_list !! (n-1)
    a179910_list = map (a000040 . (+ 1)) $ elemIndices 2 a079066_list
    -- Reinhard Zumkeller, Jul 19 2011
  • Mathematica
    f[n_] := Block[ {id = IntegerDigits@n}, len = Length@ id - 1; Count[ PrimeQ@ Union[ FromDigits@# & /@ Flatten[ Table[ Partition[ id, k, 1], {k, len}], 1]], True] + 1]; Select[ Prime@ Range@ 160, f@# == 3 &]
    Select[ Prime@ Range@ 160, Function[ n, Length@ Select[ Union[ FromDigits /@ (Flatten[ Table[ Partition[#, k, 1], {k, Length@ # - 1}], 1] &)@ IntegerDigits@ n], PrimeQ]]@ # == 2 &] (* Michael Somos, Jan 13 2011 *)
Previous Showing 11-20 of 41 results. Next