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.

Showing 1-3 of 3 results.

A178091 Emirps whose digital sums are also emirps.

Original entry on oeis.org

157, 179, 337, 359, 733, 751, 953, 971, 1097, 1237, 1259, 1381, 1439, 1453, 1471, 1583, 1619, 1723, 1741, 1831, 3019, 3109, 3163, 3257, 3271, 3343, 3347, 3433, 3527, 3541, 3613, 3851, 7253, 7321, 7433, 7523, 7699, 7879, 7901, 9013, 9103, 9161, 9341, 9521, 9679, 9769, 9787, 9967
Offset: 1

Views

Author

Lekraj Beedassy, May 19 2010

Keywords

Comments

Palindromic primes are not allowed, nor are palindromic digital sums of primes. - Harvey P. Dale, Feb 23 2014

Crossrefs

Programs

  • Mathematica
    dseQ[n_]:=Module[{idn=IntegerDigits[n],ds},ds=IntegerDigits[Total[idn]];idn!=Reverse[idn]&&ds!=Reverse[ds] && And@@PrimeQ[{FromDigits[ Reverse[ idn]],FromDigits[ds],FromDigits[Reverse[ds]]}]]; Select[Prime[Range[ 1300]],dseQ] (* Harvey P. Dale, Feb 23 2014 *)

A178093 Larger of emirp pairs whose digital sums are also emirps (A178091).

Original entry on oeis.org

733, 751, 953, 971, 1741, 1831, 3271, 3433, 3541, 3613, 3851, 7253, 7321, 7433, 7523, 7901, 9013, 9103, 9161, 9341, 9521, 9769, 9787, 9967, 13711, 14431, 14831, 15241, 15511, 15601, 15731, 16451, 17041, 18701, 19421, 30271, 30491, 30851, 31081, 31481, 31531, 32341
Offset: 1

Views

Author

Lekraj Beedassy, May 19 2010

Keywords

Crossrefs

Programs

  • Mathematica
    emirpQ[n_] := n != IntegerReverse[n] && PrimeQ[n] && PrimeQ[IntegerReverse[n]]; q[n_] := emirpQ[DigitSum[n]] && n > IntegerReverse[n] && emirpQ[n]; Select[Range[10^5], q] (* Amiram Eldar, Apr 30 2024 *)

Extensions

More terms from Amiram Eldar, Apr 30 2024

A230255 Emirps whose sum of digits is prime.

Original entry on oeis.org

113, 157, 179, 199, 311, 337, 359, 733, 739, 751, 937, 953, 971, 991, 1031, 1033, 1091, 1097, 1103, 1109, 1181, 1213, 1217, 1231, 1237, 1259, 1279, 1301, 1321, 1381, 1439, 1453, 1471, 1499, 1523, 1583, 1619, 1657, 1723, 1741, 1811, 1831, 1901, 1949, 3011, 3019
Offset: 1

Views

Author

K. D. Bajpai, Oct 14 2013

Keywords

Examples

			a(6)= 337 is emirp. Sum of digits= 3+3+7= 13 which is prime.
a(11)= 937 is emirp. Sum of digits= 9+3+7= 19 which is prime.
		

Crossrefs

Cf. A006567 (emirps: primes whose reversal is different prime).
Cf. A082806 (palindromic primes: sum of digits is prime).
Cf. A178092 (emirps: digital sum is emirp).

Programs

  • Maple
    with(StringTools):KD:= proc() local a,b,d; a:=ithprime(n);b:=parse(Reverse(convert(a,string))); d:=add( i,i = convert((a), base, 10))(a);if a<>b and isprime(b) and isprime(d) then return(a):fi; end: seq(KD(),n=1..2000);
  • Mathematica
    Select[Prime[Range[500]],!PalindromeQ[#]&&AllTrue[{IntegerReverse[#],Total[ IntegerDigits[ #]]},PrimeQ]&] (* Harvey P. Dale, Nov 01 2022 *)
Showing 1-3 of 3 results.