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 1-9 of 9 results.

A087762 Primes whose reversal is a multiple of 7.

Original entry on oeis.org

7, 19, 41, 53, 89, 103, 127, 139, 173, 197, 211, 223, 281, 293, 331, 367, 379, 463, 487, 499, 571, 691, 719, 827, 839, 911, 947, 1013, 1049, 1277, 1289, 1303, 1327, 1361, 1373, 1423, 1447, 1459, 1481, 1493, 1531, 1543, 1567, 1579, 1663, 1699, 1783, 1907
Offset: 1

Views

Author

Zak Seidov, Oct 03 2003

Keywords

Crossrefs

Primes whose reversal is a multiple of k: this sequence (k=7), A087764 (k=13), A087765 (k=17), A087766 (k=19), A087767 (k=23).

Programs

  • Mathematica
    Select[Prime[Range[300]],Divisible[FromDigits[Reverse[IntegerDigits[ #]]], 7]&] (* Harvey P. Dale, Dec 05 2012 *)
  • PARI
    forprime(n=2, 2000, if(fromdigits(Vecrev(digits(n)))%7==0, print1(n, ", "))) \\ Mohammed Yaseen, Jul 19 2022

A087764 Primes whose reversal is a multiple of 13.

Original entry on oeis.org

19, 31, 269, 281, 397, 401, 457, 463, 523, 773, 827, 1063, 1117, 1123, 1367, 1373, 1427, 1433, 1489, 1549, 1609, 1621, 1871, 1931, 1987, 1993, 2027, 2089, 2161, 2221, 2399, 2459, 2531, 2593, 2647, 2707, 2713
Offset: 1

Views

Author

Zak Seidov, Oct 03 2003

Keywords

Comments

There are no primes (besides 11) whose reversal is a multiple of 11.

Crossrefs

Primes whose reversal is a multiple of k: A087762 (k=7), this sequence (k=13), A087765 (k=17), A087766 (k=19), A087767 (k=23).

Programs

  • Maple
    digrev:= proc(n) local L, i;
      L:= convert(n,base,10);
      add(L[-i]*10^(i-1), i=1..nops(L))
    end proc:
    B:= map(digrev, {seq(i,i=13..10000,13)}):
    sort(convert(select(isprime, B),list)); # Robert Israel, Oct 23 2019
  • PARI
    forprime(n=2, 3000, if(fromdigits(Vecrev(digits(n)))%13==0, print1(n, ", "))) \\ Mohammed Yaseen, Jul 19 2022

A087765 Primes whose reversal is a multiple of 17.

Original entry on oeis.org

43, 71, 109, 137, 193, 631, 911, 997, 1049, 1291, 1543, 1571, 1609, 1637, 1693, 1759, 1787, 1823, 1973, 2053, 2081, 2269, 2297, 2333, 2549, 2699, 2707, 2791, 2857, 3001, 3217, 3581, 3769, 3797, 3833, 4007, 4091, 4129, 4157, 4409, 4493, 4651, 4903, 4931, 5011
Offset: 1

Views

Author

Zak Seidov, Oct 03 2003

Keywords

Crossrefs

Primes whose reversal is a multiple of k: A045711 (k=5), A087762 (k=7), A087764 (k=13), this sequence (k=17), A087766 (k=19), A087767 (k=23).

Programs

  • Mathematica
    Select[Prime[Range[700]],Divisible[IntegerReverse[#],17]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 25 2019 *)
  • PARI
    forprime(n=2, 6000, if(fromdigits(Vecrev(digits(n)))%17==0, print1(n, ", "))) \\ Mohammed Yaseen, Jul 20 2022

Extensions

Corrected and extended by Ray Chandler, Oct 05 2003
Corrected and extended by Harvey P. Dale, Aug 25 2019

A087767 Primes whose reversal is a multiple of 23.

Original entry on oeis.org

29, 193, 223, 317, 349, 863, 1163, 1289, 1319, 1451, 1483, 1607, 1801, 2579, 2609, 2741, 2803, 3041, 3167, 3229, 3361, 3517, 4363, 4457, 4519, 4651, 5077, 5107, 5333, 5591, 5653, 5779, 6047, 6079, 6367, 6911, 7211, 7243, 7369, 7883
Offset: 1

Views

Author

Zak Seidov, Oct 03 2003

Keywords

Crossrefs

Primes whose reversal is a multiple of k: A045711 (k=5), A087762 (k=7), A087764 (k=13), A087765 (k=17), A087766 (k=19), this sequence (k=23).

Programs

  • Mathematica
    Select[Prime[Range[1000]],Divisible[IntegerReverse[#],23]&] (* Harvey P. Dale, Apr 22 2022 *)
  • PARI
    forprime(n=2, 8000, if(fromdigits(Vecrev(digits(n)))%23==0, print1(n, ", "))) \\ Mohammed Yaseen, Jul 20 2022

A355430 Primes starting with an even decimal digit.

Original entry on oeis.org

2, 23, 29, 41, 43, 47, 61, 67, 83, 89, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 809, 811, 821
Offset: 1

Views

Author

Bernard Schott, Jul 20 2022

Keywords

Comments

Primes whose reversal is an even integer.

Examples

			43 is a term because 43 is prime and 34 is an even number.
		

Crossrefs

Intersection of A000040 and A273892.
Equals disjoint union of A045708, A045710, A045712 and A045714.
Primes whose reversal is a multiple of k: this sequence (k=2), {3} (k=3), A045711 (k=5), A087762 (k=7), {11} (k=11), A087764 (k=13), A087765 (k=17), A087766 (k=19), A087767 (k=23).

Programs

  • Mathematica
    imax=142; a={}; For[i=1, i<=imax, i++, If[EvenQ[FromDigits[Reverse[IntegerDigits[Prime[i]]]]], AppendTo[a,Prime[i]]]]; a (* Stefano Spezia, Jul 20 2022 *)
    Select[Prime[Range[200]],EvenQ[IntegerDigits[#][[1]]]&] (* Harvey P. Dale, May 18 2025 *)
  • PARI
    isok(k) = isprime(k) && !(fromdigits(Vecrev(digits(k))) % 2); \\ Michel Marcus, Jul 20 2022
    
  • Python
    from sympy import isprime
    def ok(n): return str(n)[0] in "2468" and isprime(n)
    print([k for k in range(822) if ok(k)]) # Michael S. Branicky, Jul 25 2022
    
  • Python
    from sympy import isprime
    from itertools import chain, count, islice, product
    def agen(): yield from chain((2,), (t for t in (b+i for d in count(1) for b in range(2*10**d, 10*10**d, 2*10**d) for i in range(1, 10**d, 2)) if isprime(t)))
    print(list(islice(agen(), 62))) # Michael S. Branicky, Jul 25 2022

A355983 Primes whose reversal is a multiple of 4.

Original entry on oeis.org

23, 29, 61, 67, 211, 233, 239, 251, 257, 271, 277, 293, 401, 409, 421, 443, 449, 461, 463, 467, 487, 613, 617, 619, 631, 653, 659, 673, 677, 691, 809, 821, 823, 827, 829, 863, 881, 883, 887, 2111, 2113, 2129, 2131, 2137, 2141, 2143, 2153, 2161, 2179, 2309, 2311, 2333, 2339, 2341, 2347, 2351
Offset: 1

Views

Author

Bernard Schott, Jul 22 2022

Keywords

Comments

Equivalently, primes starting with 21, 23, 25, 27, 29, 40, 42, 44, 46, 48, 61, 63, 65, 67, 69, 80, 82, 84, 86, 88.
Subsequence of A355430.

Examples

			67 is a term since 67 is prime and 76 is divisible by 4.
		

Crossrefs

Primes whose reversal is a multiple of k: A355430 (k=2), {3} (k=3), this sequence (k=4), A045711 (k=5), A087762 (k=7), {11} (k=11), A087764 (k=13), A087765 (k=17), A087766 (k=19), A087767 (k=23).

Programs

  • Mathematica
    Select[Prime[Range[350]], Divisible[IntegerReverse[#], 4] &] (* Amiram Eldar, Jul 22 2022 *)
  • PARI
    isok(p) = isprime(p) && !(fromdigits(Vecrev(digits(p))) % 4); \\ Michel Marcus, Jul 22 2022

A355984 Primes whose reversal is a multiple of 8.

Original entry on oeis.org

23, 61, 211, 251, 257, 293, 401, 409, 443, 449, 487, 631, 673, 677, 821, 823, 827, 829, 863, 2111, 2113, 2131, 2137, 2153, 2179, 2309, 2341, 2347, 2381, 2383, 2389, 2531, 2539, 2551, 2557, 2579, 2591, 2593, 2707, 2729, 2741, 2749, 2767, 2789, 2917, 2939, 2953, 2957
Offset: 1

Views

Author

Bernard Schott, Jul 25 2022

Keywords

Comments

Subsequence of A355430 and of A355983.

Examples

			251 is a term since 251 is prime and 152 = 8 * 19.
		

Crossrefs

Primes whose reversal is a multiple of k: A355430 (k=2), {3} (k=3), A355983 (k=4), A045711 (k=5), A087762 (k=7), this sequence (k=8), {11} (k=11), A087764 (k=13), A087765 (k=17), A087766 (k=19), A087767 (k=23)

Programs

  • Mathematica
    Select[Prime[Range[500]], Divisible[IntegerReverse[#], 8] &] (* Amiram Eldar, Jul 25 2022 *)
  • PARI
    is(n) = fromdigits(Vecrev(digits(n)))%8 == 0 \\ David A. Corneth, Jul 25 2022

Extensions

More terms from David A. Corneth, Jul 25 2022

A355985 Primes whose reversal is a multiple of 16.

Original entry on oeis.org

23, 61, 211, 257, 449, 487, 821, 829, 863, 2131, 2137, 2179, 2551, 2557, 2591, 2593, 2707, 2741, 2749, 2789, 2939, 2971, 4013, 4019, 4051, 4057, 4091, 4093, 4099, 4201, 4241, 4243, 4283, 4289, 4621, 4663, 4813, 4817, 6121, 6163, 6311, 6317, 6353, 6359, 6397
Offset: 1

Views

Author

Bernard Schott, Jul 29 2022

Keywords

Examples

			257 is a term since 257 is prime and 752 = 16 * 47.
		

Crossrefs

Subsequence of A355430, A355983 and A355984.
Primes whose reversal is a multiple of k: A355430 (k=2), {3} (k=3), A355983 (k=4), A045711 (k=5), A087762 (k=7), A355984 (k=8), {11} (k=11), A087764 (k=13), this sequence (k=16), A087765 (k=17), A087766 (k=19), A087767 (k=23).

Programs

  • Mathematica
    Select[Prime[Range[1000]], Divisible[IntegerReverse[#], 16] &] (* Amiram Eldar, Jul 29 2022 *)
  • PARI
    is(n) = { fromdigits(Vecrev(digits(n)))%16==0 && isprime(n) } \\ Rémy Sigrist, Jul 29 2022

Extensions

More terms from Rémy Sigrist, Jul 29 2022

A356246 Primes whose reversal is a multiple of 14.

Original entry on oeis.org

41, 89, 211, 223, 281, 293, 463, 487, 499, 691, 827, 839, 2129, 2213, 2237, 2333, 2357, 2441, 2477, 2503, 2539, 2647, 2659, 2693, 2731, 2767, 2851, 2887, 2971, 4021, 4057, 4091, 4153, 4177, 4261, 4273, 4297, 4409, 4517, 4637, 4649, 4721, 4733, 4877, 4889, 4903, 4973
Offset: 1

Views

Author

Bernard Schott, Jul 30 2022

Keywords

Comments

Intersection of A087762 and A355430.

Examples

			281 is a term since 281 is prime and 182 = 14 * 13.
		

Crossrefs

Primes whose reversal is a multiple of k: A074895 (k=1), A355430 (k=2), {3} (k=3), A355983 (k=4), A045711 (k=5), A087762 (k=7), A355984 (k=8), {11} (k=11), A087764 (k=13), this sequence (k=14), A355985 (k=16), A087765 (k=17), A087766 (k=19), A087767 (k=23).

Programs

  • Mathematica
    Select[Prime[Range[666]], Divisible[IntegerReverse[#], 14] &] (* Amiram Eldar, Jul 30 2022 *)
Showing 1-9 of 9 results.