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.

A285096 Primes with integer arithmetic mean of digits = 2 in base 10.

Original entry on oeis.org

2, 13, 31, 1061, 1151, 1223, 1511, 1601, 2141, 2213, 2411, 3023, 3041, 3203, 3221, 4013, 4211, 5003, 5021, 6011, 6101, 7001, 10009, 10243, 10333, 10513, 10531, 10711, 11071, 11161, 11251, 11503, 11701, 12007, 12043, 12241, 12421, 12511, 12601, 13033, 13411
Offset: 1

Views

Author

Jaroslav Krizek, Apr 16 2017

Keywords

Crossrefs

Primes in A061385. Subsequence of A069709.
Sequences of primes such that a(n) = k for k = 1, 2, 4, 5, 7 and 8: A069710 (k = 1), this sequence (k = 2), A285225 (k = 4), A285226 (k = 5), A285227 (k = 7), A285228 (k = 8).

Programs

  • Magma
    [n: n in [1..100000] | IsPrime(n) and &+Intseq(n) mod #Intseq(n) eq 0 and &+Intseq(n) / #Intseq(n) eq 2];
  • Maple
    S:= proc(d,k,flag) option remember;
      if d = 1 then
        if k >= 0 and k <= 9 then return [k]
        else return []
        fi
      fi;
      [seq(op(map(`+`, procname(d-1,k-i,0), i*10^(d-1))),i=flag..min(k,9))]
    end proc:
    seq(op(select(isprime,S(d,2*d,1))),d=1..5);# Robert Israel, Apr 23 2017
  • Mathematica
    Select[Prime[Range[1600]],Mean[IntegerDigits[#]]==2&] (* Harvey P. Dale, Aug 07 2021 *)