cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A363391 Numbers k such that k, k+1, k+2, k+3 have 2, 3, 4, 5 prime factors respectively, counted with multiplicity.

Original entry on oeis.org

493, 2413, 3013, 3427, 3873, 4333, 4885, 5029, 5893, 6697, 7373, 8373, 10113, 10533, 13011, 14005, 14677, 15122, 16373, 17173, 17869, 18613, 19693, 20053, 20613, 22417, 23073, 23077, 23137, 23573, 24493, 24613, 24937, 25141, 26101, 26193, 26917, 27637, 27973, 28357, 29713, 29941, 31861, 32393
Offset: 1

Views

Author

Zak Seidov and Robert Israel, Jun 23 2023

Keywords

Comments

Numbers k such that A001222(k+j) = 2+j for j = 0,1,2,3.
The first k in the sequence such that A001222(k+4) = 6 is a(232) = 153221.
The first k in the sequence such that A001222(k+4) = 6 and A001222(k+5) = 7 is a(4716) = 2940571.

Examples

			a(3) = 3013 is a term because 3013 = 23 * 131 has 2 prime factors counted by multiplicity, 3014 = 2 * 11 * 137 has 3, 3015 = 3^2 * 5 * 67 has 4, and 3016 = 2^3 * 13 * 29 has 5.
		

Crossrefs

Programs

  • Maple
    R:= NULL: state:= 0: count:= 0:
    for x from 1 while count < 50 do
      v:= numtheory:-bigomega(x);
      if v = 2 then state:= 2
      elif v = state+1 and state >= 2 then state:=state+1
      else state:= 0
      fi;
      if state = 5 then count:= count+1; R:= R,x-3;
      fi;
    od:
    R;
Previous Showing 11-11 of 11 results.