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 11-13 of 13 results.

A143863 Primes such that the sum of digits is a perfect power (A001597).

Original entry on oeis.org

13, 17, 31, 53, 71, 79, 97, 103, 107, 211, 233, 251, 277, 349, 367, 431, 439, 457, 503, 521, 547, 619, 673, 691, 701, 709, 727, 853, 907, 997, 1021, 1061, 1069, 1087, 1151, 1201, 1223, 1249, 1429, 1447, 1483, 1511, 1601, 1609, 1627, 1663, 1699, 1753, 1789
Offset: 1

Views

Author

Giovanni Teofilatto, Sep 04 2008

Keywords

Crossrefs

Cf. A062338.

Programs

  • Mathematica
    Select[Prime[Range[300]],GCD@@FactorInteger[Total[IntegerDigits[#]]][[;;,2]]>1&] (* Harvey P. Dale, Sep 18 2023 *)

Formula

Union of A062339, A062343, A106757, A106768, A107618 etc. [From R. J. Mathar, Sep 13 2008]

Extensions

389, 569, 581, 659, 677 etc. removed by R. J. Mathar, Sep 13 2008

A158283 Prime numbers p such that 1 = abs(final digit of p - sum of all the other digits of p).

Original entry on oeis.org

23, 43, 67, 89, 113, 157, 179, 199, 223, 269, 313, 337, 359, 379, 449, 607, 719, 739, 809, 829, 919, 1013, 1033, 1103, 1123, 1213, 1237, 1259, 1279, 1303, 1327, 1439, 1459, 1549, 1619, 1709, 2003, 2069, 2089, 2113, 2137, 2179, 2203, 2269, 2339, 2539
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Mar 15 2009

Keywords

Examples

			23(1=3-2), 43(1=abs(3-4)), 67(1=abs(7-6)), 89(1=abs(9-8)), 113(1=3-(1+1)).
		

Crossrefs

Programs

  • Mathematica
    ps1[n_]:=Module[{idn=IntegerDigits[n]},Abs[Last[idn]-Total[Most[idn]]] == 1]; Select[Prime[Range[400]],ps1] (* Harvey P. Dale, Jul 31 2012 *)

Extensions

Entries checked by R. J. Mathar, May 19 2010

A158571 Primes whose digit sum is a single-digit nonprime.

Original entry on oeis.org

13, 17, 31, 53, 71, 103, 107, 211, 233, 251, 431, 503, 521, 701, 1021, 1061, 1151, 1201, 1223, 1511, 1601, 2011, 2141, 2213, 2411, 3001, 3023, 3041, 3203, 3221, 4013, 4211, 5003, 5021, 6011, 6101, 7001, 10007, 10061, 10111, 10133, 10151, 10223, 10313
Offset: 1

Views

Author

Parthasarathy Nambi, Mar 21 2009

Keywords

Comments

It is interesting to observe that it is hard to find (I found none) primes whose digit sum is 6. On the contrary, it is easier to find primes whose digit sum is 8.
The digit sum 6 does not occur here because a number with digit sum 6 is divisible by 3 and therefore not prime. - R. J. Mathar, Mar 26 2009

Examples

			1061 is a prime whose digit sum is 8, which is a single-digit nonprime.
		

Crossrefs

Cf. A158217.

Programs

  • Maple
    for i from 1 to 8 do if member(i,[1,3,7]) then S[1,i]:= {i} else S[1,i]:= {} fi od:
    for d from 2 to 5 do
      for x from 1 to 8 do
        S[d,x]:= {};
        for y from 0 to x-1 do
          S[d,x]:= S[d,x] union map(t -> 10^(d-1)*y + t, S[d-1,x-y])
    od od od:
    select(isprime, S[5,4] union S[5,8]); # Robert Israel, Apr 14 2021

Formula

Union of A062339 and A062343. - R. J. Mathar, Mar 26 2009

Extensions

Extended by R. J. Mathar, Mar 26 2009
Previous Showing 11-13 of 13 results.