A024967 Positions of primes in A003072.

1, 3, 5, 7, 11, 17, 25, 28, 34, 38, 39, 41, 46, 48, 53, 57, 68, 72, 73, 77, 80, 91, 100, 108, 110, 113, 115, 116, 120, 123, 128, 135, 144, 156, 161, 175, 185, 189, 198, 202, 205, 217, 224, 231, 235, 245, 247, 252, 255, 267, 273, 275, 276, 278, 285, 297, 301, 304, 315, 320, 324

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..8446

Programs

Maple

N:= 10000: # for members of A003072 up to N
S:= {}:
for x from 1 while 3*x^3 <= N do
  for y from x while x^3+2*y^3<=N do
    for z from y do
      v:= x^3+y^3+z^3;
      if v > N then break fi;
      S:= S union {v}
od od od:
S:= sort(convert(S,list)):
select(i -> isprime(S[i]),[$1..nops(S)]); # Robert Israel, Aug 27 2019

Extensions

More terms from Sean A. Irvine, Jul 30 2019