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.

A046368 Products of two palindromic primes.

Original entry on oeis.org

4, 6, 9, 10, 14, 15, 21, 22, 25, 33, 35, 49, 55, 77, 121, 202, 262, 302, 303, 362, 382, 393, 453, 505, 543, 573, 626, 655, 706, 707, 746, 755, 766, 905, 917, 939, 955, 1057, 1059, 1111, 1119, 1149, 1267, 1337, 1441, 1454, 1514, 1565, 1574, 1594, 1661, 1765, 1838, 1858
Offset: 1

Views

Author

Patrick De Geest, Jun 15 1998

Keywords

Comments

Intersection of A001358 and A033620; A046368 is a subsequence. - Reinhard Zumkeller, Apr 10 2011
Equivalently, semiprimes where both prime factors are palindromes. - Franklin T. Adams-Watters, Apr 11 2011
See A046376 for the subsequence of palindromic terms. - M. F. Hasler, Jan 04 2022

Links

Crossrefs

Cf. A001358 (semiprimes), A002113 (palindromes), A002385 (palindromic primes), A046376 (subsequence of palindromes), A046400.

Programs

  • Mathematica
    palQ[n_] := Reverse[x = IntegerDigits[n]] == x; Select[Range[1800], PrimeOmega[#] == 2 && And @@ palQ /@ First /@ FactorInteger[#] &] (* Jayanta Basu, Jun 23 2013 *)
  • PARI
    select( {is_A046368(n)=bigomega(n)==2 && vecmin( apply( is_A002113, factor(n)[, 1]))}, [1..9999]) \\ M. F. Hasler, Jan 04 2022

Extensions

Definition clarified by Franklin T. Adams-Watters, Apr 11 2011
Definition simplified by M. F. Hasler, Jan 04 2022

A046403 Numbers with exactly 5 distinct palindromic prime factors.

Original entry on oeis.org

2310, 21210, 27510, 31710, 33330, 38010, 40110, 43230, 46662, 49830, 59730, 60522, 63030, 65730, 69762, 74130, 77770, 78330, 80430, 83622, 88242, 100870, 103290, 116270, 116490, 116655, 123090, 126390, 139370, 144606, 147070, 151305, 152670, 158970, 163086, 165270, 167370
Offset: 1

Views

Author

Patrick De Geest, Jun 15 1998

Keywords

Examples

			144606 = 2 * 3 * 7 * 11 * 313 is in the sequence as it has exactly 5 prime factors each of which is a palindrome. - _David A. Corneth_, Aug 30 2020

Links

Crossrefs

Cf. A002385, A014614, A046400, A046401, A046402, A046403, A046371.

Extensions

Offset changed to 1 and more terms from David A. Corneth, Aug 30 2020

A164374 Numbers that are the sum of 2 distinct palindromic primes.

Original entry on oeis.org

5, 7, 8, 9, 10, 12, 13, 14, 16, 18, 103, 104, 106, 108, 112, 133, 134, 136, 138, 142, 153, 154, 156, 158, 162, 183, 184, 186, 188, 192, 193, 194, 196, 198, 202, 232, 252, 282, 292, 312, 315, 316, 318, 320, 322, 324, 332, 342, 355, 356, 358, 360, 364, 372, 375, 376, 378
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Aug 14 2009

Keywords

Comments

Numbers of the form A002385(i)+A002385(j), i<> j.

Examples

			a(1)=2+3=5. a(2)=2+5=7. a(3)=3+5=8. 11+191=202. 101+131=232.

Crossrefs

Cf. A002385, A046400, A115683.

Programs

Extensions

Missing numbers inserted by R. J. Mathar, Aug 26 2009
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.