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.

A230852 Smallest k<3*2^n such that 3*2^n+k is the smallest of four consecutive primes in arithmetic progression or 0 if no solution.

Original entry on oeis.org

0, 0, 0, 0, 0, 59, 0, 0, 205, 229, 167, 353, 1595, 4459, 6407, 6215, 14995, 4559, 4697, 11399, 365, 10199, 19327, 39103, 3185, 13649, 15787, 2693, 21455, 24929, 32209, 30509, 13421, 5389, 36947, 12869, 27277, 38389, 973, 69199, 58835, 165629, 52597, 25463, 17923, 38629, 90263, 17153, 48143, 2171, 1255
Offset: 1

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Author

Pierre CAMI, Oct 31 2013

Keywords

Comments

Conjecture: if n>8 there is always a solution.

Examples

			3*2^6+59=251, and 251, 257, 263, 269 are four consecutive primes in arithmetic progression 6 so a(6)=59.
3*2^9+205=1741, and 1741, 1747, 1753, 1759 are four consecutive primes in arithmetic progression 6 so a(9)=205.
		

Crossrefs

Programs

  • PARI
    cpap4(p)=my(q=nextprime(p+1),g=q-p);nextprime(q+1)-q==g&&nextprime(p+2*g+1)==p+3*g
    a(n)=forprime(p=3<Charles R Greathouse IV, Oct 31 2013

A231576 Sequence of pairs k,g such that k is the smallest odd number and k*2^n-1-g, k*2^n-1, k*2^n-1+g are three consecutive primes in arithmetic progression.

Original entry on oeis.org

3, 2, 53, 12, 33, 6, 69, 6, 19, 6, 2193, 12, 93, 6, 113, 6, 87, 6, 413, 12, 1165, 12, 143, 6, 237, 6, 47, 6, 315, 18, 779, 6, 631, 30, 797, 6, 735, 12, 567, 18, 397, 6, 351, 24, 195, 18, 39, 36, 2719, 6, 971, 6, 1369, 30, 635, 18, 1501, 12, 593, 72, 2053, 6
Offset: 1

Views

Author

Pierre CAMI, Nov 11 2013

Keywords

Examples

			3*2^1-1-2=3, 3*2^1-1=5, 3*2^1-1+2=7, so first pair = 3,2 (the only one with g=2).
53*2^2-1-12=199, 53*2^2-1=211, 53*2^2-1+12=223, so second pair = 53,12.
		

Crossrefs

A227856 Sequence of pairs k,g with k<3*2^n the smallest such that 3*2^n+k, 3*2^n+k+g, 3*2^n+k+2*g are three consecutive primes in arithmetic progression starting at n=5 as there is not any solution for n<5.

Original entry on oeis.org

55, 6, 7, 12, 173, 6, 173, 6, 205, 6, 229, 6, 113, 6, 203, 6, 95, 6, 475, 6, 163, 6, 119, 12, 377, 18, 1045, 6, 133, 12, 551, 24, 131, 12, 259, 6, 1105, 42, 539, 6, 1487, 18, 1295, 12, 5, 12, 289, 36, 311, 36, 269, 6, 2833, 6, 1813, 18, 835, 6, 319, 6, 587, 6, 239, 30, 1225, 6, 1825, 12, 973, 12, 89, 30, 551, 12, 1805, 30, 1039, 18, 1219, 6
Offset: 5

Views

Author

Pierre CAMI, Nov 01 2013

Keywords

Comments

The ratio k/n^2 is in average near 0.8 and < 7 for n<701.
The ratio g/n^2 is in average near 0.5 and < 4 for n<701.
If 3*2^n+k > 10^22 the numbers are probable primes.

Examples

			3*2^5+55=151, 3*2^5+55+6=157 3*2^5+55*2*6=163
151, 157, 163 three consecutive primes in arithmetic progression 6, so first pair is 55, 6
		

Crossrefs

Showing 1-3 of 3 results.