A387081 Indices k such that lpf(s(k)) != lpf(s(k-1)), where s = A386482 and lpf = A020736.

2, 5, 11, 16, 17, 24, 31, 41, 44, 49, 52, 57, 70, 73, 76, 100, 103, 106, 115, 121, 125, 126, 139, 144, 176, 189, 194, 205, 207, 236, 275, 287, 299, 310, 320, 363, 368, 431, 453, 479, 615, 634, 647, 650, 652, 661, 662, 667, 674, 678, 684, 737, 785, 788, 800, 801

Offset: 1

Author

Michael De Vlieger, Aug 19 2025

Keywords

• nonn
• new

Comments

A387077 appears to be a proper subset. This is to say the indices of primes in A386482 appear in this sequence.

Examples

			Table of n, a(n), relating these to s = A387482:
 n a(n)=k  s(k-1) s(k) s(k+1)
-----------------------------
 1     2     1     2     4
 2     5     6     3     9
 3    11    14     7    21
 4    16    20    15     5
 5    17    15     5    25
 6    24    22    11    33
 7    31    38    19    57
 8    41    40    35    45
 9    44    39    13    65
10    49    56    49    63
11    52    51    17    68
12    57    62    31    93
23   139   152   171   165
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..26018

Crossrefs

Cf. A020736, A386482, A387077, A387079.

Programs

Mathematica

s = Import["https://oeis.org/A386482/b386482.txt","Data"][[ ;; , -1]]; j = 1; {2}~Join~Reap[Do[If[! Divisible[Abs[j - s[[n]]], FactorInteger[j][[1, 1]] ], Sow[n]]; j = s[[n]], {n, 2, Length[s]}] ][[-1, 1]]