A035031 For n >= 7, max(A151799(n), 2*A151799(floor((n-1)/2))).

1, 2, 2, 3, 3, 5, 5, 7, 7, 7, 7, 11, 11, 13, 13, 13, 14, 17, 17, 19, 19, 19, 19, 23, 23, 23, 23, 23, 26, 29, 29, 31, 31, 31, 31, 31, 34, 37, 37, 37, 38, 41, 41, 43, 43, 43, 43, 47, 47, 47, 47, 47, 47, 53, 53, 53, 53, 53

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

References

• S. K. Stein and S. Szabo, Algebra and Tiling, MAA Carus Monograph 25, 1994, page 104.

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A035032, A151799.

Programs

Maple

f:= proc(n) max(prevprime(n), 2*prevprime(floor((n-1)/2))) end proc:
for i from 1 to 6 do f(i):= [1, 2, 2, 3, 3, 5, 5][i] od:
map(f, [$1..100]); # Robert Israel, Dec 15 2023

Mathematica

Join[{1,2},Table[Max[NextPrime[n,-1],2NextPrime[Floor[(n-1)/2],-1]],{n,3,70}]] (* Harvey P. Dale, Mar 12 2022 *)