[seqfan] Two related simple infinite sequences

[zak seidov]

s1 = {5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 17, 16, 19, 18, 21, 20, 23, 22, 25, 24, 29, 28, 31, 30, 33, 32, 37, 36, 41, 40, 43, 42, 46, 45, 47, 46, 49, 48, 51, 50, 53, 52, 55, 54, 57, 56, 59, 58, 61, 60, 65, 64, 67, 66, 69, 68, 71, 70, 73, 72, 77, 76, 79, 78, 81, 80, 82, 81, 83, 82, 85, 84, 89, 88, 91, 90, 93, 92, 97, 96, 101, 100, 103, 102, 105, 104, 106, 105, 107, 106, 109, 108, 111, 110, 113, 112, 115, 114, 118, 117, 121, 120, 127, 126, 129, 128, 131, 130, 133, 132, 137, 136, 139, 138, 141, 140, 145, 144, 149, 148, 151, 150, 153, 152, 155, 154, 157, 156, 161, 160, 163, 162, 166, 165, 167, 166, 169, 168, 173, 172, ...}

s2 = {2, 1, 4, 3, 6, 5, 8, 7, 12, 11, 14, 13, 16, 15, 18, 17, 20, 19, 24, 23, 27, 26, 30, 29, 32, 31, 36, 35, 38, 37, 40, 39, 42, 41, 44, 43, 48, 47, 50, 49, 52, 51, 54, 53, 56, 55, 60, 59, 62, 61, 63, 62, 64, 63, 66, 65, 68, 67, 70, 69, 72, 71, 74, 73, 75, 74, 78, 77, 80, 79, 84, 83, 88, 87, 90, 89, 92, 91, 96, 95, 98, 97, 100, 99, 102, 101, 104, 103, 108, 107, 110, 109, 112, 111, 114, 113, 116, 115, 120, 119, 124, 123, 126, 125, 128, 127, 130, 129, 132, 131, 135, 134, 138, 137, 140, 139, 144, 143, 147, 146, 150, 149, 152, 151, 156, 155, 158, 157, 160, 159, 162, 161, 164, 163, 168, 167, 170, 169, 174, 173, 176, 175, ...}

Can anyone guess what s1 and s2 are? 
Zak Seidov
zakseidov at Yahoo.com