a(1) = 2 = (3 - 2) * (7 - 5)
a(2) = 3 = 2 + 3 + 5 - 7
a(3) = 5 = 5 * (7 - 2 * 3)
a(4) = 7 = (2 + 3 - 5 + 7
a(5) = 11 = 2 - 3 + 5 + 7
a(6) = 13 = 7 + 5 - 2 + 3
a(7) = 17 = 2 + 3 + 5 + 7
a(8) = 19 = 27 - (3 + 5)
a(9) = 23 = 5 * (2 * 3) - 7
a(10) = 29 = 25 - 3 + 7
a(11) = 31 = 2 * 5 + 3 * 7
a(12) = 37 = 7 + 2 * 3 * 5
a(13) = 41 = 2 * 3 + 5 * 7
a(14) = 43 = 2 ^ 3 + 5 * 7
a(15) = 47 = 7 + 5 * 2 ^ 3
a(16) = 53 = 2 ^ 5 + 3 * 7
a(17) = 59 = (5 ^ 3 - 7)/ 2
a(18) = 61 = 5 + 7 * (2 ^ 3)
a(19) = 67 = 2 * 5 * 7 - 3
a(20) = 71 = 7 + (3 + 5) ^ 2
a(21) = 73 = 3 + 2 * 5 * 7
a(22) = 79 = 5 + 2 * 37
a(23) = 83 = 2 ^ 3 + 75
a(24) = 89 = 3 * 2 ^ 5 - 7
a(25) = 103 = 3 * 2 ^ 5 + 7
a(26) = 107 = 32 + 75
a(27) = 113 = 2 ^ 7 - 3 * 5
a(28) = 139 = 2 * 7 + 5 ^ 3
a(29) = 149 = 3 * 52 - 7
a(30) = 151 = 5 + 2 * 73
a(31) = 163 = 2 ^ 7 + 35
a(32) = 167 = 7 + 5 * 32
a(33) = 173 = 2 + 3 * 57
a(34) = 181 = 2 ^ 7 + 53
a(35) = 197 = 5 ^ 3 + 72
a(36) = 211 = 3 * 72 - 5
a(37) = 223 = 3 * 75 - 2
a(38) = 227 = 3 + 7 * 2 ^ 5
a(39) = 229 = 5 + 7 * 32
a(40) = 257 = 2 * 7 + 3 ^ 5
a(41) = 263 = 7 + 2 ^ (3 + 5)
a(42) = 311 = 7 ^ 3 - 2 ^ 5
a(43) = 353 = 2 * 5 + 7 ^ 3
a(44) = 359 = 352 + 7
a(45) = 367 = 372 - 5
a(46) = 373 = 375 - 2
a(47) = 379 = 3 * 2 ^ 7 - 5
a(48) = 389 = 3 * 2 ^ 7 + 5
a(49) = 479 = 2 * 3 ^ 5 - 7
a(50) = 569 = 572 - 3
a(51) = 571 = 573 - 2
a(52) = 643 = 3 + 5 * 2 ^ 7
a(53) = 691 = 5 + 2 * 7 ^ 3
a(54) = 727 = 732 - 5
a(55) = 733 = 735 - 2
a(56) = 751 = 753 - 2
a(57) = 877 = 2 + 7 * 5 ^ 3
a(58) = 1019 = 2 ^ (3 + 7) - 5
a(59) = 1091 = (3 ^ 7 - 5) / 2
a(60) = 1699 = 7 * 3 ^ 5 - 2
a(61) = 2239 = 3 ^ 7 + 52
a(62) = 2357 = 2357
a(63) = 2749 = 5 + (2 * 7) ^ 3
a(64) = 2753 = 2753
a(65) = 3257 = 3257
a(66) = 3527 = 3527
a(67) = 4093 = 2 ^ (5 + 7) - 3
a(68) = 4099 = 3 + 2 ^ (5 + 7)
a(69) = 5237 = 5237
a(70) = 5273 = 5273
a(71) = 7253 = 7253
a(72) = 7523 = 7523
a(73) = 10937 = 2 + 5 * (3 ^ 7)
a(74) = 26041 = ((5 ^ 7) - 2) / 3
a(75) = 33617 = 3 + 2 * 7 ^ 5
a(76) = 50423 = 2 + 3 * 7 ^ 5
a(77) = 78157 = 32 + 5 ^ 7
a(78) = 156253 = 3 + 2 * 5 ^ 7
a(79) = 279941 = 5 + (2 * 3) ^ 7
a(80) = 5764799 = 7 ^ (3 + 5) - 2
a(81) = 170859373 = (3 * 5)^7 - 2
a(82) = 1174711139839 = 2 + 53 ^ 7
a(83) = 4747561509941 = 7 ^ (3 * 5) - 2