A328459 Sorted positions of first appearances in A328458 (maximum run-length of nontrivial divisors) of each positive integer in the image.

1, 2, 6, 12, 60, 420, 504, 840, 2520, 27720, 360360, 720720, 4084080

Offset

0,2

Links

Table of n, a(n) for n=0..12.

Example

The sequence of terms > 1 together with their nontrivial divisors begins:
    2: {}
    6: {2,3}
   12: {2,3,4,6}
   60: {2,3,4,5,6,10,12,15,20,30}
  420: {2,3,4,5,6,7,10,12,14,15,20,21,28,30,35,42,60,70,84,105,140,210}
  504: {2,3,4,6,7,8,9,12,14,18,21,24,28,36,42,56,63,72,84,126,168,252}

Mathematica

dav=Table[Switch[n, 1, 1, _, Max@@Length/@Split[DeleteCases[Divisors[n], 1|n], #2==#1+1&]], {n, 1000}];
Table[Position[dav, i][[1, 1]], {i, Union[dav]}]//Sort

Crossrefs

Positions of first appearances in A328458.

The version for all divisors is A051451.

Cf. A000005, A033676, A060775, A070824, A119313, A129308, A181063, A199970, A163870, A328448, A328449.

Sequence in context: A048803 A068625 A162935 * A051451 A090951 A168262

Adjacent sequences: A328456 A328457 A328458 * A328460 A328461 A328462

Keyword

nonn,more

Author

Gus Wiseman, Oct 17 2019

Extensions

a(12) from Robert Israel, Mar 31 2023

Status

approved