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.

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A034303 Zeroless primes that become nonprime if any digit is deleted.

Original entry on oeis.org

11, 19, 41, 61, 89, 227, 251, 257, 277, 281, 349, 449, 499, 521, 557, 577, 587, 727, 757, 787, 821, 827, 857, 877, 881, 887, 991, 1117, 1129, 1171, 1187, 1259, 1289, 1423, 1447, 1453, 1471, 1483, 1543, 1553, 1559, 1583, 1621, 1669, 1721, 1741, 1747
Offset: 1

Views

Author

Keywords

Crossrefs

Programs

  • Haskell
    import Data.List (inits, tails)
    a034303 n = a034303_list !! (n-1)
    a034303_list = filter f $ drop 4 a038618_list where
       f x = all (== 0) $ map (a010051 . read) $
                 zipWith (++) (inits $ show x) (tail $ tails $ show x)
    -- Reinhard Zumkeller, Dec 17 2011
  • Mathematica
    Select[Prime[Range[5,300]],Union[PrimeQ[FromDigits/@Table[Delete[ IntegerDigits[ #], n],{n,IntegerLength[#]}]]] == {False} && !MemberQ[ IntegerDigits[#],0]&] (* Harvey P. Dale, Jan 09 2014 *)

Extensions

Definition corrected by T. D. Noe, Apr 02 2008
Name edited by Jon E. Schoenfield, Feb 07 2022

A057628 Primes such that replacing each digit d with d copies of the digit d produces a prime. Zeros are not allowed.

Original entry on oeis.org

11, 31, 53, 131, 149, 223, 283, 311, 313, 331, 397, 463, 641, 691, 937, 941, 1439, 1511, 1741, 1871, 1949, 1993, 1999, 2111, 2447, 2939, 3163, 3391, 3433, 3499, 3559, 3593, 3659, 3911, 3931, 5227, 5399, 5923, 6163, 6269, 6653, 6719, 7177, 7741, 8389
Offset: 1

Views

Author

G. L. Honaker, Jr., Oct 10 2000

Keywords

Comments

"Replacing each digit d with d copies of the digit d" is the function A048376. Therefore this is the largest subset of A038618 stable under the map A048376.

Examples

			E.g. 641 becomes 66666644441 which is also prime.
		

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[1500]],PrimeQ[FromDigits[Flatten[Table[#,{#}]&/@ IntegerDigits[#]]]]&&DigitCount[#,10,0]==0&]  (* Harvey P. Dale, Mar 27 2011 *)
  • PARI
    is_A057628(n)={vecmin(digits(n)) && is_A057630(n)} \\ M. F. Hasler, Jan 23 2013

Extensions

More terms from Patrick De Geest, Oct 15 2000.
Offset changed to 1, according to OEIS conventions, by M. F. Hasler, Jan 23 2013

A101987 Product of nonzero digits of n-th prime.

Original entry on oeis.org

2, 3, 5, 7, 1, 3, 7, 9, 6, 18, 3, 21, 4, 12, 28, 15, 45, 6, 42, 7, 21, 63, 24, 72, 63, 1, 3, 7, 9, 3, 14, 3, 21, 27, 36, 5, 35, 18, 42, 21, 63, 8, 9, 27, 63, 81, 2, 12, 28, 36, 18, 54, 8, 10, 70, 36, 108, 14, 98, 16, 48, 54, 21, 3, 9, 21, 9, 63, 84, 108, 45, 135, 126, 63, 189, 72, 216
Offset: 1

Views

Author

Zak Seidov, Jan 29 2005

Keywords

Comments

First differs from A053666 in 26th term.

Examples

			a(25) = 63 because the 25th prime is 97 and 9 * 7 = 63.
a(26) = 1 because the 26th prime is 101, but we ignore the 0 and thus have 1 * 1 = 1.
		

Crossrefs

Programs

  • Maple
    a:= n-> mul(`if`(i=0, 1, i), i=convert(ithprime(n), base, 10)):
    seq(a(n), n=1..77);  # Alois P. Heinz, Mar 11 2022
  • Mathematica
    Table[Times@@ReplaceAll[IntegerDigits[Prime[n]], 0 -> 1], {n, 80}] (* Alonso del Arte, Feb 28 2014 *)
  • PARI
    a(n) = vecprod(select(x->(x>1), digits(prime(n)))); \\ Michel Marcus, Mar 11 2022
    
  • Python
    from math import prod
    from sympy import sieve
    def A051801(n): return prod(int(d) for d in str(n) if d != '0')
    def a(n): return A051801(sieve[n])
    print([a(n) for n in range(1, 78)]) # Michael S. Branicky, Mar 11 2022

Formula

a(n) = A051801(prime(n)). - Michel Marcus, Mar 11 2022

A106101 Primes with minimal digit = 1.

Original entry on oeis.org

11, 13, 17, 19, 31, 41, 61, 71, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 241, 251, 271, 281, 311, 313, 317, 331, 419, 421, 431, 461, 491, 521, 541, 571, 613, 617, 619, 631, 641, 661, 691, 719, 751, 761, 811
Offset: 1

Views

Author

Zak Seidov, May 07 2005

Keywords

Comments

Subsequence of A038618. - Michel Marcus, Oct 23 2013

Crossrefs

Cf. A038618.

Programs

  • Mathematica
    Select[Prime[Range[200]], Min[IntegerDigits[ # ]]==1&]

A386320 Primes without {0, 2} as digits.

Original entry on oeis.org

3, 5, 7, 11, 13, 17, 19, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 113, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 419, 431, 433, 439
Offset: 1

Views

Author

Jason Bard, Jul 18 2025

Keywords

Crossrefs

Intersection of A038604 and A038618.

Programs

  • Magma
    [p: p in PrimesUpTo(10^6) | Set(Intseq(p)) subset [1, 3, 4, 5, 6, 7, 8, 9]];
    
  • Mathematica
    Select[Prime[Range[120]], DigitCount[#, 10, 0] == 0 && DigitCount[#, 10, 2] == 0 &]
  • PARI
    primes_with(, 1, [1, 3, 4, 5, 6, 7, 8, 9]) \\ uses function in A385776
  • Python
    print(list(islice(primes_with("13456789"), 41))) # uses function/imports in A385776
    

A220488 Primes that have both prime digits (2,3,5,7) and nonprime digits (1,4,6,8,9), without digits "0".

Original entry on oeis.org

13, 17, 29, 31, 43, 47, 59, 67, 71, 79, 83, 97, 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, Feb 01 2013

Keywords

Comments

For similar sequences see A152426 and A152427.

Crossrefs

Programs

A228139 Primes such that the product of their digits subtracted from the prime number is another prime.

Original entry on oeis.org

23, 29, 41, 43, 47, 83, 89, 127, 149, 181, 223, 227, 229, 241, 251, 263, 271, 277, 293, 347, 349, 367, 383, 389, 419, 431, 433, 439, 457, 479, 487, 541, 587, 631, 641, 643, 647, 653, 659, 673, 677, 743, 761, 853, 857, 859, 863, 883, 887, 1123, 1229, 1279, 1297, 1423, 1459, 1489, 1523
Offset: 1

Views

Author

Will Gosnell, Aug 12 2013

Keywords

Examples

			23 is a member since 23-(2*3)=17. 29 is a member since 29-(2*9)=11.
		

Crossrefs

Subsequence of A038618.

Programs

  • Mathematica
    pdsQ[n_]:=Module[{pr=Times@@IntegerDigits[n]},pr!=0&&PrimeQ[n-pr]]; Select[Prime[Range[300]],pdsQ] (* Harvey P. Dale, Jul 29 2017 *)
  • PARI
    dprod(n)=my(v=digits(n));prod(i=1,#v,v[i])
    is(n)=my(d=dprod(n)); d>0 && isprime(n) && isprime(n-d) \\ Charles R Greathouse IV, Aug 12 2013

Extensions

a(3), a(10), a(15)-a(57) from Charles R Greathouse IV, Aug 12 2013

A259315 Nonprimes containing no zeros in decimal representation.

Original entry on oeis.org

1, 4, 6, 8, 9, 12, 14, 15, 16, 18, 21, 22, 24, 25, 26, 27, 28, 32, 33, 34, 35, 36, 38, 39, 42, 44, 45, 46, 48, 49, 51, 52, 54, 55, 56, 57, 58, 62, 63, 64, 65, 66, 68, 69, 72, 74, 75, 76, 77, 78, 81, 82, 84, 85, 86, 87, 88, 91, 92, 93, 94, 95, 96, 98, 99, 111
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 24 2015

Keywords

Comments

Intersection of A052382 and A018252;
A168046(a(n)) * (1 - A010051(a(n))) = 1.

Crossrefs

Programs

  • Haskell
    a259315 n = a259315_list !! (n-1)
    a259315_list = filter ((== 0) . a010051') a052382_list
    
  • Mathematica
    Select[Range[150],!PrimeQ[#]&&DigitCount[#,10,0]==0&] (* Harvey P. Dale, Sep 18 2024 *)
  • PARI
    isok(m) = !isprime(m) && vecmin(digits(m)); \\ Michel Marcus, Jan 23 2022

A346206 Primes p, with k digits, such that the Sum_{i=1..k} (p without its i-th digit)/(its i-th digit) is a prime.

Original entry on oeis.org

11, 21673, 27367, 32611, 33311, 41141, 48821, 82781, 171263, 211441, 243433, 323443, 343243, 449699, 632623, 663661, 727271, 772127, 847871, 882881, 944969, 1129699, 1192699, 1193939, 1262633, 1334341, 1342433, 1343423, 1361441, 1388641, 1399193, 1461883, 1613441
Offset: 1

Views

Author

Michel Marcus, Jul 10 2021

Keywords

Examples

			21673 gives 1673/2 + 2673/1 + 2173/6 + 2163/7 + 2167/3 = 4903; so 21673 is a term.
		

Crossrefs

Subsequence of A038618 (zeroless primes).

Programs

  • PARI
    subs(d, j) = {my(x=""); for (k=1, #d, if (j != k, x = concat(x, d[k]));); eval(x);}
    isok(p) = {my(d=digits(p), res);  if (isprime(p) && vecmin(d), res = sum(j=1, #d, subs(d, j)/d[j]); (denominator(res)==1) && isprime(res););}
    
  • Python
    from sympy import isprime, primerange
    from fractions import Fraction
    def ok(p):
        s = str(p)
        if '0' in s or len(s) == 1: return False
        f = sum(Fraction(int(s[:i]+s[i+1:]), int(s[i])) for i in range(len(s)))
        return f.denominator == 1 and isprime(f.numerator)
    def aupto(lim): return [p for p in primerange(1, lim+1) if ok(p)]
    print(aupto(1620000)) # Michael S. Branicky, Jul 11 2021

A134873 Primes p with the property that the sum of the digits of the product of the digits of p is also a prime number.

Original entry on oeis.org

2, 3, 5, 7, 13, 17, 31, 37, 43, 71, 73, 113, 127, 131, 137, 151, 173, 211, 223, 257, 271, 277, 281, 311, 317, 431, 457, 523, 541, 547, 557, 577, 727, 757, 821, 853, 1117, 1151, 1171, 1187, 1217, 1223, 1277, 1427, 1451, 1481, 1511, 1523
Offset: 1

Views

Author

Erich Leistenschneider (el(AT)erichl.net), Feb 01 2008

Keywords

Examples

			2531 is a member of this sequence because it is a prime number and the product of its digits is 2*5*3*1 = 30 and the sum of the digits of this result is 3+0 = 3, which is also a prime number.
		

Crossrefs

Subsequence of A038618 (zeroless primes).

Programs

  • Maple
    a:=proc(n) local dn,pr,dpr: dn:=convert(n,base,10): pr:=mul(dn[i],i=1..nops(dn)): dpr:=convert(pr,base,10): if isprime(n)=true and isprime(add(dpr[j],j= 1..nops(dpr)))=true then n else end if end proc: seq(a(n),n=1..1600); # Emeric Deutsch, Mar 01 2008
  • Mathematica
    Select[Prime[Range[300]],PrimeQ[Total[IntegerDigits[Times@@ IntegerDigits[#]]]]&] (* Harvey P. Dale, Dec 15 2011 *)
  • PARI
    isok(p) = isprime(p) && isprime(sumdigits(vecprod(digits(p)))); \\ Michel Marcus, Jan 16 2019
Previous Showing 31-40 of 56 results. Next