A249991 Start with the natural numbers, reverse the order in each pair, skip one number, reverse the order in each triple, skip one number, and so on.

2, 3, 5, 10, 12, 13, 21, 26, 28, 39, 41, 46, 54, 65, 67, 82, 84, 85, 109, 114, 122, 137, 139, 160, 178, 179, 181, 222, 230, 235, 269, 274, 276, 313, 331, 336, 370, 381, 383, 424, 426, 437, 471, 476, 536, 541, 549, 554, 618, 629, 647, 704, 706, 707, 761, 818

Offset: 1

Author

Alex Ratushnyak, Nov 27 2014

Keywords

• nonn

Comments

Start with the natural numbers. Reverse the order of numbers in each pair. Skip one number. In the remainder (that is, "1, 4, 3, 6, 5, 8, 7, 10, 9, 12, 11,...") reverse the order in each triple. Skip one number. In the remainder (it starts with "4, 1, 8, 5, 6, 9, 10, 7") reverse the order in each tetrad. Skip one number. And so on.

Crossrefs

Cf. A000960, A026239, A249990.

Partial sums of A057031.

Programs

Python

TOP = 100000
a = list(range(TOP))
for step in range(2,TOP):
  numBlocks = (len(a)-1) // step
  if numBlocks==0:  break
  a = a[:(1+numBlocks*step)]
  for pos in range(1,len(a),step):
    a[pos:pos+step] = a[pos+step-1:pos-1:-1]
  print(a[1], end=', ')
  a[1:] = a[2:]