A000954 -id:A000954 - cp's OEIS frontend

A352305 a(n) is the (conjectured) largest even number that can be expressed as the sum of two distinct primes in exactly n ways.

6, 38, 68, 128, 158, 188, 398, 362, 458, 542, 632, 692, 602, 992, 808, 908, 1112, 1238, 1412, 1418, 1718, 1544, 1574, 1622, 1682, 2048, 2252, 2018, 2672, 2042, 2558, 2936, 2504, 2978, 2966, 3092, 3218, 3242, 3272, 3506, 3632, 3754, 4022, 4058, 4052, 4412, 4448, 4478

Offset: 0

Ilya Gutkovskiy, Mar 11 2022

nonn

			a(5) = 188 because 188 = 7 + 181 = 31 + 157 = 37 + 151 = 61 + 127 = 79 + 109 and it is conjectured that 188 is the last term of A080854.

Cf. A000954, A038609, A061357, A077914, A077969, A078299, A080854, A080862, A087747, A117929, A212613.

More terms from Hugo Pfoertner, Dec 18 2024

A352298 Conjectured largest number that can be expressed as the sum of two primes in exactly n ways or -1 if no such number exists.

Original entry on oeis.org

-1, -1, 68, 128, 152, 188, 332, 398, 368, 488, 632, 692, 626, 992, 878, 908, 1112, 998, 1412, 1202, 1448, 1718, 1532, 1604, 1682, 2048, 2252, 2078, 2672, 2642, 2456, 2936, 2504, 2588, 2978, 3092, 3032, 3218, 3272, 3296, 3632, 3548, 3754, 4022, 4058, 4412, 4448

Offset: 0

Chai Wah Wu, Mar 11 2022

sign

Conjecture A in page 32 of the Hardy and Littlewood reference implies that a(n) != -1 for all n > 1. While the sequence is not monotonic, the plot of n versus a(n)/log(a(n))^2 has a linear trend which matches with the formula for the number of representations in Conjecture A.

G. H. Hardy and J. E. Littlewood, Some problems of 'Partitio numerorum'; III: On the expression of a number as a sum of primes, Acta Mathematica, volume 44, pages 1-70 (1923).

Cf. A352296.

Essentially the same as A000954.

cp's OEIS Frontend

A352305 a(n) is the (conjectured) largest even number that can be expressed as the sum of two distinct primes in exactly n ways.

Views

Author

Keywords

Examples

Crossrefs

Extensions

A352298 Conjectured largest number that can be expressed as the sum of two primes in exactly n ways or -1 if no such number exists.

Views

Author

Keywords

Comments

Links

Crossrefs