A145092 Indices of the prime numbers after mapping the positive integers onto successive rings of length {1, 5, 30, 180, 1080, ...} and assigning index 0 to the smallest value in each.

0, 1, 3, 0, 4, 6, 10, 12, 16, 22, 24, 0, 4, 6, 10, 16, 22, 24, 30, 34, 36, 42, 46, 52, 60, 64, 66, 70, 72, 76, 90, 94, 100, 102, 112, 114, 120, 126, 130, 136, 142, 144, 154, 156, 160, 162, 174, 6, 10, 12, 16, 22, 24, 34, 40, 46, 52, 54, 60, 64, 66, 76, 90, 94, 96, 100, 114

Offset

1,3

Comments

After the second ring, all primes have indices that are congruent to 0 or 4 modulo 6, because index 0 is given to a value congruent to 1 (one greater than a power of six).

Links

Table of n, a(n) for n=1..67.

Example

The first three rings contain these numbers:
1
.
2 3 4 5 6 (sequence begins here)
0 1 . 3 .
.........
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 ...
0 . . .. .4 .. .6 .. .. .. 10 .. 12 .. .. .. 16 .. .. .. .. .. 22 .. 24 .. .. .. .. ...

Crossrefs

Cf. A000040, A008588, A016957

Sequence in context: A112238 A111493 A190181 * A210878 A355977 A356581

Adjacent sequences: A145089 A145090 A145091 * A145093 A145094 A145095

Keyword

easy,nonn

Author

Reikku Kulon, Oct 01 2008

Status

approved