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

1,1

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.

Links

Table of n, a(n) for n=1..56.

Prog

(Python)
TOP = 100000
a = 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 str(a[1])+', ',
..a[1:] = a[2:]

Crossrefs

Cf. A000960, A026239, A249990.

Partial sums of A057031.

Sequence in context: A192229 A233696 A002263 * A039022 A182402 A079251

Adjacent sequences: A249988 A249989 A249990 * A249992 A249993 A249994

Keyword

nonn

Author

Alex Ratushnyak, Nov 27 2014

Status

approved