A023202 -id:A023202 - cp's OEIS frontend

A164385 Composite numbers n such that n+4 and n-4 are both prime.

9, 15, 27, 33, 57, 63, 75, 93, 105, 135, 153, 177, 195, 237, 267, 273, 363, 393, 405, 435, 453, 483, 495, 567, 573, 597, 603, 657, 687, 705, 723, 747, 765, 825, 915, 933, 987, 1017, 1035, 1065, 1113, 1167, 1197, 1227, 1233, 1287, 1293, 1323, 1377, 1443, 1455, 1485

Offset: 1

Juri-Stepan Gerasimov, Aug 14 2009

nonn

Composite numbers of the form A023202(k)+4, any k.
A087680 without the {7} [Proof: there are no 3 primes in arithmetic progression p, p+4, p+8, except p=3].
A164383 INTERSECT A164384; A087680 INTERSECT A002808.
If p=3*l+1, p+8 were divisible by 3, and if p=3*l+2, p+4 were divisible by 3. - R. J. Mathar, Aug 20 2009
All terms are divisible by 3. - Zak Seidov, Apr 22 2015

			a(1) = 5(prime)+4 = 13(prime)-4 = 9 (composite).
a(2) = 11(prime)+4 = 19(prime)-4 = 15 (composite).

Cf. A002808, A023202, A087680.

[n: n in [8..2000] | IsPrime(n+4) and IsPrime(n-4)]; // Vincenzo Librandi, Apr 22 2015

Select[Range[8, 2000], PrimeQ[#+4] && PrimeQ[#-4] &] (* Vincenzo Librandi, Apr 22 2015 *)
Select[Range[9,5000],AllTrue[#+{4,-4},PrimeQ]&] (* Harvey P. Dale, Mar 23 2025 *)

a(n) = A023202(n+1)+4 = A087680(n+1). - Zak Seidov, Apr 22 2015

65 removed, 337 changed to 237 etc. by R. J. Mathar, Aug 20 2009

A213210 Numbers n such that n and n + 8 are prime and there is a power of two in the interval (n,n+8).

Original entry on oeis.org

3, 5, 11, 29, 59, 4091, 262139

Offset: 1

Brad Clardy, Mar 02 2013

nonn

It is a conjecture that this sequence is finite. A search around 2^n was done up to 2^1500.

Cf. A023202, A221211.

//Program finds primes separated by an even number (called gap) which
//have a power of two between them. The program starts with the smallest
//power of two above gap. Primes less than this starting point can be
//checked inspection. In this example 3 and 5 also work.
gap:=8;
start:=Ilog2(gap)+1;
for i:= start to 1000 do
    powerof2:=2^i;
    for k:=powerof2-gap+1 to powerof2-1 by 2 do
        if (IsPrime(k) and IsPrime(k+gap)) then k;
        end if;
    end for;
end for;

[n: n in PrimesUpTo(10^6) | IsPrime(n+8) and exists{t: t in [n+1..n+7 by 2] | IsOne(t/2^Valuation(t,2))}]; // Bruno Berselli, May 16 2013

A240986 Determinants of n X n matrices of sets of distinct primes selected by increasing prime gaps (see comments).

Original entry on oeis.org

3, 6, -36, -216, 1296, -5184, -145152, -3856896, -170325504, -6133211136, 1094593056768, 26742290558976, -497681937801216, -14357497419546624, 657148066947072000, 12008320398059765760, 1322255096225695531008, 70546799432003423698944, -6537119853797882157072384, -27940593871362459110473728

Offset: 1

Samuel J. Erickson, Aug 06 2014

sign

Let P = {3,5,7,11,...} be the sequence of odd primes and let P(k) = {prime in P: (prime+2k) is in P} (although set builder notation is used for P(k) we will still assume that P(k) is a sequence). Let M(n) be the n X n matrix where row 1 is the first n elements from P(1), row 2 is the first n elements from P(2), and in general row j is the first n elements from P(j). This sequence is the sequence of determinants for M(1), M(2), M(3), M(4), ..., M(9).

			For the first element of the sequence we find the determinant of the matrix [[3,5],[3,7]], where [3,5] is row 1 and [3,7] is row 2. These numbers are there because in row 1 we are looking at the primes where we can add 2 to get another prime; 3+2 is prime and so is 5+2, so they go in row 1. Similarly, for the second row we get [3,7] because these are the first primes such that when 4 is added we get a prime: 3+4 and 7+4 are both prime, so they go in row 2. For the second entry in the sequence we take the determinant of [[3,5,11],[3,7,13],[5,7,11]]; the reason we get [5,7,11] in the third row is because 5 is the first prime where 5+6 is prime, 7 is second prime where 7+6 is prime, and 11 is the third prime where 11+6 is prime.

Jinyuan Wang, Table of n, a(n) for n = 1..200
Samuel J. Erickson, Python Code
Sachin Joglekar, Determinant of matrix of any order (Python)

Cf. A001359, A023200, A023201, A023202, A023203.

a(n) = {my(m=matrix(n,n), j); for (i=1, n, j = 1; forprime(p=2, , if (isprime(p+2*i), m[i,j] = p; j++); if (j > n, break););); matdet(m);} \\ Michel Marcus, May 04 2019

Python
```
# See Erickson link.
```

Offset 1 and more terms from Michel Marcus, May 04 2019

A274506 Primes one less than the sum over a pair of prime numbers that differ by 8.

Original entry on oeis.org

13, 17, 29, 53, 113, 149, 269, 353, 389, 809, 1193, 1373, 1409, 1493, 1973, 2069, 2129, 2333, 2393, 2753, 2909, 2969, 3209, 4013, 4493, 4673, 5333, 5693, 6029, 6089, 6449, 6653, 7253, 7529, 7829, 7853, 8429, 8513, 9173, 9293, 10889, 10949, 11393, 11489, 11633, 12413, 12713, 12953, 13049, 13313, 14249, 14969

Offset: 1

Debapriyay Mukhopadhyay, Jun 25 2016

nonn

Any prime p in this sequence is such that p = (p-7)/2 + (p+9)/2 - 1, where (p-7)/2 and (p+9)/2 are also primes and they differ by 8.

			13 = 3 + 11 - 1. Note that, (13-7)/2 = 3 and (13+9)/2 = 11 and the prime pairs 3 and 11 differ by 8.
17 = 5 + 13 - 1. Note that, (17-7)/2 = 5 and (17+9)/2 = 13 and the prime pairs 5 and 13 differ by 8.

Cf. A023202, A274507.

Select[2 Select[Prime@ Range@ 1100, PrimeQ[# + 8] &] + 7, PrimeQ] (* Michael De Vlieger, Jun 26 2016 *)

lista(nn) = forprime(p=3, nn, if (isprime((p-7)/2) && isprime((p+9)/2), print1(p, ", "));); \\ Michel Marcus, Jun 25 2016

use ntheory ":all"; say for grep{is_prime($)} map { $+$+8-1 } sieve_prime_cluster(1,5e7,8); # _Dana Jacobsen, Apr 27 2017

A274507 Primes one more than the sum over a pair of prime numbers that differ by 8.

Original entry on oeis.org

19, 31, 67, 127, 151, 211, 271, 307, 547, 727, 787, 811, 907, 967, 991, 1447, 1531, 1831, 1867, 2131, 2467, 2647, 2887, 2971, 3967, 5107, 5227, 5407, 5431, 5827, 6091, 6427, 6451, 6607, 6907, 6991, 7411, 8191, 8431, 8707, 9511, 10111

Offset: 1

Debapriyay Mukhopadhyay, Jun 25 2016

nonn

Any prime p in this sequence is such that p = (p-9)/2 + (p+7)/2 + 1, where (p-9)/2 and (p+7)/2 are also primes and they differ by 8.

This sequence is infinite under Dickson's conjecture. - Charles R Greathouse IV, Jul 08 2016

			19 = 5 + 13 + 1. Note that, (19-9)/2 = 5 and (19+7)/2 = 13 and the prime pairs 5 and 13 differ by 8.
31 = 11 + 19 + 1. Note that, (31-9)/2 = 11 and (31+7)/2 = 19 and the prime pairs 11 and 19 differ by 8.

Cf. A023202, A274506.

A subsequence of A068229 and also of A145472.

Select[2 # + 9 &@ Select[Prime@ Range[10^3], PrimeQ[# + 8] &], PrimeQ] (* Michael De Vlieger, Jun 26 2016 *)

lista(nn)=forprime(p=3, nn, if (isprime(p+8) && isprime(q=2*p+9), print1(q, ", "))); \\ Michel Marcus, Jun 25 2016

A128928 Smallest member p of a triple of primes (p,p+8,p+20).

Original entry on oeis.org

3, 11, 23, 53, 59, 89, 131, 173, 191, 263, 359, 389, 401, 479, 593, 599, 653, 719, 1013, 1031, 1109, 1193, 1229, 1283, 1439, 1451, 1523, 1559, 1601, 1733, 1979, 2273, 2531, 2663, 2699, 2711, 3041, 3209, 3251, 3299, 3323, 3449, 3491, 3539, 3623, 3719, 3911, 3923, 4091, 4211

Offset: 1

J. M. Bergot, Apr 25 2007

nonn

A subsequence of A023202. The definition implies that the sum of the first two primes, 2(p+4), divides the sum of the product of the first two primes and the last, p(p+8)+p+20=(p+4)(p+5). This feature is shared with A022005 and common to prime triples of the format (p,p+2*a,p+a+a^2) with even a. - R. J. Mathar, Apr 26 2007

Cf. A022005.

isA128928 := proc(n) isprime(n) and isprime(n+8) and isprime(n+20) ; end: for n from 1 to 300 do if isA128928(ithprime(n)) then printf("%d,",ithprime(n)) ; fi ; od ; # R. J. Mathar, Apr 26 2007

kmax = 580; Select[ Prime[ Range[1, kmax] ], (PrimeQ[ # + 8] && PrimeQ[ # + 20])& ] (* Stuart Clary *)

Corrected and extended by Robert G. Wilson v, R. J. Mathar and Stuart Clary, Apr 26 2007

A257105 Composite numbers n such that n'=(n+8)', where n' is the arithmetic derivative of n.

Original entry on oeis.org

132, 476, 2108, 16748, 27548, 28676, 99524, 100076, 239948, 308228, 344129, 573476, 601676, 822908, 860276, 883268, 1673228, 3274010, 4959476, 7548956, 8916044, 9048428, 9215348, 9643169, 9833588, 10011908, 14773676, 17119436, 18529964, 19459028, 21335948, 21739148

Offset: 1

Paolo P. Lava, Apr 17 2015

nonn

If the limitation of being composite is removed we also have the numbers p such that if p is prime then p + 8 is prime too (A023202).

			132' = (132 + 8)' = 140' = 188;
476' = (476 + 8)' = 484' = 572.

Cf. A003415, A023202, A226779.

with(numtheory); P:= proc(q,h) local a,b,n,p;
for n from 1 to q do if not isprime(n) then a:=n*add(op(2,p)/op(1,p),p=ifactors(n)[2]); b:=(n+h)*add(op(2,p)/op(1,p),p=ifactors(n+h)[2]);
if a=b then print(n); fi; fi; od; end: P(10^9,8);

a[n_] := If[Abs@ n < 2, 0, n Total[#2/#1 & @@@ FactorInteger[Abs@ n]]];
Select[Range@ 100000, And[CompositeQ@ #, a@# == a[# + 8]] &] (* Michael De Vlieger, Apr 22 2015, after Michael Somos at A003415 *)

A309392 Square array read by downward antidiagonals: A(n, k) is the k-th prime p such that p + 2*n is also prime, or 0 if that prime does not exist.

Original entry on oeis.org

3, 5, 3, 11, 7, 5, 17, 13, 7, 3, 29, 19, 11, 5, 3, 41, 37, 13, 11, 7, 5, 59, 43, 17, 23, 13, 7, 3, 71, 67, 23, 29, 19, 11, 5, 3, 101, 79, 31, 53, 31, 17, 17, 7, 5, 107, 97, 37, 59, 37, 19, 23, 13, 11, 3, 137, 103, 41, 71, 43, 29, 29, 31, 13, 11, 7, 149, 109

Offset: 1

Felix Fröhlich, Jul 28 2019

The same as A231608 except that A231608 gives the upward antidiagonals of the array, while this sequence gives the downward antidiagonals.
Conjecture: All values are nonzero, i.e., for any even integer e there are infinitely many primes p such that p + e is also prime.
The conjecture is true if Polignac's conjecture is true.

			The array starts as follows:
3,  5, 11, 17, 29, 41, 59,  71, 101, 107, 137, 149, 179, 191
3,  7, 13, 19, 37, 43, 67,  79,  97, 103, 109, 127, 163, 193
5,  7, 11, 13, 17, 23, 31,  37,  41,  47,  53,  61,  67,  73
3,  5, 11, 23, 29, 53, 59,  71,  89, 101, 131, 149, 173, 191
3,  7, 13, 19, 31, 37, 43,  61,  73,  79,  97, 103, 127, 139
5,  7, 11, 17, 19, 29, 31,  41,  47,  59,  61,  67,  71,  89
3,  5, 17, 23, 29, 47, 53,  59,  83,  89, 113, 137, 149, 167
3,  7, 13, 31, 37, 43, 67,  73,  97, 151, 157, 163, 181, 211
5, 11, 13, 19, 23, 29, 41,  43,  53,  61,  71,  79,  83,  89
3, 11, 17, 23, 41, 47, 53,  59,  83,  89, 107, 131, 137, 173
7, 19, 31, 37, 61, 67, 79, 109, 127, 151, 157, 211, 229, 241
5,  7, 13, 17, 19, 23, 29,  37,  43,  47,  59,  73,  79,  83

Wikipedia, Polignac's conjecture

Cf. A231608.

Cf. A001359 (row 1), A023200 (row 2), A023201 (row 3), A023202 (row 4), A023203 (row 5), A046133 (row 6), A153417 (row 7), A049488 (row 8), A153418 (row 9), A153419 (row 10), A242476 (row 11), A033560 (row 12), A252089 (row 13), A252090 (row 14), A049481 (row 15), A049489 (row 16), A252091 (row 17), A156104 (row 18), A271347 (row 19), A271981 (row 20), A271982 (row 21), A272176 (row 22), A062284 (row 25), A049490 (row 32), A020483 (column 1).

row(n, terms) = my(i=0); forprime(p=1, , if(i>=terms, break); if(ispseudoprime(p+2*n), print1(p, ", "); i++))
array(rows, cols) = for(x=1, rows, row(x, cols); print(""))
array(12, 14) \\ Print initial 12 rows and 14 columns of the array

cp's OEIS Frontend

A164385 Composite numbers n such that n+4 and n-4 are both prime.

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A213210 Numbers n such that n and n + 8 are prime and there is a power of two in the interval (n,n+8).

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Magma

Magma

A240986 Determinants of n X n matrices of sets of distinct primes selected by increasing prime gaps (see comments).

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PARI

Python

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A274506 Primes one less than the sum over a pair of prime numbers that differ by 8.

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A274507 Primes one more than the sum over a pair of prime numbers that differ by 8.

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Mathematica

PARI

A128928 Smallest member p of a triple of primes (p,p+8,p+20).

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Maple

Mathematica

Extensions

A257105 Composite numbers n such that n'=(n+8)', where n' is the arithmetic derivative of n.

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Comments

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Crossrefs

Programs

Maple

Mathematica

A309392 Square array read by downward antidiagonals: A(n, k) is the k-th prime p such that p + 2*n is also prime, or 0 if that prime does not exist.

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