Hello SeqFan, consider this array where the 1st column is made of all prime numbers, and the nth term of a row is 2 times the previous one on the same row [P(n)=P*2^n]: p px2 px4 px8 px16 px32 px64 px128 px256 px512 2 4 8 16 32 64 128 256 512 1024 ... 3 6 12 24 48 96 192 384 768 1536 ... 5 10 20 40 80 160 320 640 1280 2560 ... 7 14 28 56 112 224 448 896 1792 3584 ... 11 22 44 88 176 352 704 1408 2816 5632 ... 13 26 52 104 208 416 832 1664 3328 6656 ... 17 34 68 136 272 544 1088 2176 4352 8704 ... 19 38 76 152 304 608 1216 2432 4864 9728 ... 23 46 92 184 368 736 1472 2944 5888 11776 ... 29 58 116 232 464 928 1856 3712 7424 14848 ... 31 62 124 248 496 992 1984 3968 7936 15872 ... 37 74 148 296 592 1184 2368 4736 9472 18944 ... 41 82 164 328 656 1312 2624 5248 10496 20992 ... 43 86 172 344 688 1376 2752 5504 11008 22016 ... 47 94 188 376 752 1504 3008 6016 12032 24064 ... 53 106 212 424 848 1696 3392 6784 13568 27136 ... .. ... ... ... 1) The missing integers in this array are : 1 9 15 18 21 25 27 30 33 35 36 39 42 45 ... ...which (except the first term 1) are A093642. 2) The main diagonal (NW-SE) reads: 2 6 20 56 176 416 1088 2432 5888 14848 ... ...which is not in the OEIS 3) Other diagonals (NE-SW) sum up to: 2 = 2 (4+3) = 7 (8+6+5) = 19 (16+12+10+7) = 45 (38+24+20+14+11) = 101 (64+48+40+28+22+13) = 215 ... this is not in the OEIS . 4) If one keeps only the "primitive terms" of A093642 one gets: A093642 : 1 9 15 18 21 25 27 30 33 35 36 39 42 45 49 50 "primitives": 1 9 15 .. 21 25 .. .. 33 35 .. 39 .. .. 49 .. ... and again, this is not in the OEIS : 1 9 15 21 25 33 35 39 49 ... If this is of interest, could someone kindly check, compute more terms and enter those sequences in the OEIS? Best, Angelini & Wajnberg