A234320 Largest number that is not the sum of distinct primes of the form 2k+1, 4k+1, 4k+3, 6k+1, 6k+5, ...; or 0 if none exists.

9, 121, 55, 205, 161

Offset: 1

Author

Jonathan Sondow, Dec 28 2013

Keywords

• nonn
• more

Comments

Largest number that is not the sum of distinct primes of the form 2nk+r for fixed n > 0 and 0 < r < 2n with gcd(2n,r) = 1.

n = 1: Dressler proved that 9 is the largest integer which is not the sum of distinct odd primes.

n = 2 and 3: Makowski proved that the largest integer that is not the sum of distinct primes of the form 4k+1, 4k+3, 6k+1, 6k+5 is 121, 55, 205, 161, respectively.

n = 6: Dressler, Makowski, and Parker proved that the largest integer that is not the sum of distinct primes of the form 12k+1, 12k+5, 12k+7, 12k+11 is 1969, 1349, 1387, 1475.

For n = 4, 5, 7, 8, 9, ..., the largest number that is not the sum of distinct primes of the form 2nk+r seems to be unknown.

Examples

			The positive integers that are not the sum of distinct odd primes are A231408 = 1, 2, 4, 6, 9, so a(1) = A231408(5) = 9.
		

References

• A. Makowski, Partitions into unequal primes, Bull. Acad. Polon. Sci. Sér. Math. Astronom. Phys., 8 (1960), 125-126.

Links

• R. E. Dressler, A stronger Bertrand's postulate with an application to partitions, Proc. Amer. Math. Soc., 33 (1972), 226-228.
• R. E. Dressler, Addendum to "A stronger Bertrand's postulate with an application to partitions", Proc. Am. Math. Soc., 38 (1973), 667.
• R. E. Dressler, A. Makowski, and T. Parker, Sums of Distinct Primes from Congruence Classes Modulo 12, Math. Comp., 28 (1974), 651-652.
• T. Kløve, Sums of Distinct Elements from a Fixed Set, Math. Comp., 29 (1975), 1144-1149.

Crossrefs

Cf. A231407, A231408.