A142190 -id:A142190 - cp's OEIS frontend

A244505 Greater of twin primes of (40n-23,40n-21).

19, 139, 619, 859, 1699, 2659, 3259, 4219, 4339, 5419, 5659, 7459, 8539, 9859, 10459, 10939, 11059, 11779, 12379, 13219, 13339, 15139, 15739, 17419, 17659, 19699, 20899, 21019, 21379, 21739, 22699, 23059, 23539, 24979, 25579, 27739, 28099, 30139, 32059

Offset: 1

Karl V. Keller, Jr., Nov 11 2014

nonn

This is a subsequence and the intersection of A006512 (greater of twin primes) and A142190 (primes 19 mod 40).

Karl V. Keller, Jr., Table of n, a(n) for n = 1..10000
Chris K. Caldwell, Twin primes
Eric Weisstein's World of Mathematics, Twin Primes

Cf. A142190, A006512.

Select[40*Range[1000]-21,AllTrue[{#,#-2},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Oct 04 2019 *)

lista(nn) = for(n=1, nn, if(isprime(q=40*n-21) && isprime(q-2), print1(n, ", "))); \\ Michel Marcus, Nov 12 2014

from sympy import isprime
for n in range(1,2001):
  if isprime(40*n-23) and isprime(40*n-21): print(40*n-21,end=",")

A250024 a(n) = 40*n - 21.

Original entry on oeis.org

19, 59, 99, 139, 179, 219, 259, 299, 339, 379, 419, 459, 499, 539, 579, 619, 659, 699, 739, 779, 819, 859, 899, 939, 979, 1019, 1059, 1099, 1139, 1179, 1219, 1259, 1299, 1339, 1379, 1419, 1459, 1499, 1539, 1579, 1619, 1659, 1699, 1739, 1779, 1819, 1859, 1899

Offset: 1

Karl V. Keller, Jr., Nov 10 2014

This is the sequence of numbers congruent to 19 mod 40.

Karl V. Keller, Jr., Table of n, a(n) for n = 1..10000
Tanya Khovanova, Recursive Sequences.
Index entries for linear recurrences with constant coefficients, signature (2,-1).

Cf. A017377 (10*n+9), A142190 (prime terms).

[40*n-21: n in [1..60]]; // Vincenzo Librandi, Nov 11 2014

40 Range[40] - 21 (* Alonso del Arte, Nov 10 2014 *)
CoefficientList[Series[(19 + 21 x) / (1 - x)^2, {x, 0, 50}], x] (* Vincenzo Librandi, Nov 11 2014 *)

a(n)=40*n-21 \\ Charles R Greathouse IV, May 23 2019

for n in range(1,101): print(40*n-21,end=",")

From Vincenzo Librandi, Nov 11 2014: (Start)
G.f.: x*(19+21*x)/(1-x)^2.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). (End)
From Elmo R. Oliveira, Apr 04 2025: (Start)
E.g.f.: 21 + exp(x)*(40*x - 21).
a(n) = 2*a(n-1) - a(n-2) for n > 2. (End)

A250025 Lesser of twin prime pairs of the form (40n - 21, 40n - 19).

Original entry on oeis.org

59, 179, 419, 659, 1019, 1619, 2339, 3299, 3539, 4019, 4259, 5099, 6299, 6659, 6779, 8219, 8819, 9419, 10139, 10499, 10859, 11699, 11939, 12539, 16139, 16979, 17579, 18059, 18539, 19139, 19379, 21059, 22619, 22739, 22859, 24179, 24419, 26699, 27059, 27539, 28619, 32939, 33179, 34259, 34499, 36779, 36899, 37019, 38459

Offset: 1

Karl V. Keller, Jr., Nov 10 2014

nonn

This is a subsequence and the intersection of A001359 (lesser of twin primes) and A142190 (primes 19 mod 40).

Karl V. Keller, Jr., Table of n, a(n) for n = 1..10000
Chris K. Caldwell, Twin primes
Eric Weisstein's World of Mathematics, Twin Primes

Cf. A142190, A001359.

Select[40Range[1000] - 21, PrimeQ[#] && PrimeQ[# + 2] &] (* Alonso del Arte, Nov 11 2014 *)
Select[Table[40n-{19,21},{n,1000}],AllTrue[#,PrimeQ]&][[All,2]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Apr 08 2019 *)

from sympy import isprime
for n in range(1,1001):
  if isprime(40*n-21) and isprime(40*n-19): print(40*n-21,end=",")

cp's OEIS Frontend

A244505 Greater of twin primes of (40n-23,40n-21).

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A250024 a(n) = 40*n - 21.

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A250025 Lesser of twin prime pairs of the form (40n - 21, 40n - 19).

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Mathematica

Python