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.

A359332 Numbers with arithmetic derivative which is a palindromic prime number (A002385).

Original entry on oeis.org

6, 10, 114, 130, 174, 182, 222, 231, 255, 273, 286, 298, 357, 358, 455, 574, 622, 870, 1015, 1309, 1335, 1677, 1695, 12594, 13630, 13686, 15258, 18534, 18654, 19082, 19114, 19522, 19626, 19922, 19986, 20998, 21558, 22178, 22882, 22930, 23062, 23262, 23709, 24338
Offset: 1

Views

Author

Marius A. Burtea, Jan 29 2023

Keywords

Comments

A subsequence of A157037.
If p and q, (p < q), are twin primes and q is a term in A002385, then m = 2*p is a term. Indeed, m' = (2*p)' = p + 2 = q, which is a palindromic prime number (A157037).

Examples

			6' = 5 = A002385(3).
114' = 101 = A002385(6).
		

Crossrefs

Programs

  • Magma
    f:=func;
    pal:=func;
    [p:p in [1..25000]|pal(Floor(f(p))) and IsPrime(Floor(f(p)))];
  • Maple
    d:= n-> n*add(i[2]/i[1], i=ifactors(n)[2]):
    q:= n-> (k-> isprime(k) and StringTools[IsPalindrome](""||k))(d(n)):
    select(q, [$1..25000])[];  # Alois P. Heinz, Jan 29 2023
  • Mathematica
    d[0] = d[1] = 0; d[n_] := n * Plus @@ ((Last[#]/First[#]) & /@ FactorInteger[n]); Select[Range[25000], PrimeQ[p = d[#]] && PalindromeQ[p] &] (* Amiram Eldar, Jan 29 2023 *)