A097752 Least integer with each "mod 4 prime signature".

1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 21, 24, 25, 27, 30, 32, 36, 40, 42, 45, 48, 50, 54, 60, 63, 64, 65, 72, 75, 80, 81, 84, 90, 96, 100, 105, 108, 120, 125, 126, 128, 130, 135, 144, 150, 160, 162, 168, 180, 189, 192, 195, 200, 210, 216, 225, 231, 240, 243

Offset: 1

Author

Ray Chandler, Aug 26 2004

Keywords

• nonn

Comments

See A097751 for definition of "mod 4 prime signature".

A097751 sorted and duplicates removed; n such that A097751(n)=n.

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
• Charles R Greathouse IV, PARI/GP script to find terms of this sequence

Crossrefs

Cf. A097751, A097753, A097754, A097755, A097756.

Programs

Mathematica

mod4PrimeSignature[n_] := {fi = FactorInteger[n]; If[OddQ[n], 0, fi[[1, 2]]], Select[fi, Mod[#[[1]], 4] == 3 &][[All, 2]]//Sort, Select[fi, Mod[#[[1]], 4] == 1 &][[All, 2]]}; A097751[n_] := Catch[For[k = 2, True, k++, If[ mod4PrimeSignature[k] == mod4PrimeSignature[n], Throw[k]]]]; A097751[1] = 1; Select[ Range[243], A097751[#] == # &] (* Jean-François Alcover, Jan 10 2013 *)

PARI

is(n)=n>>=valuation(n,2); my(e3=valuation(n,3),e1=valuation(n,5),e); n/=3^e3 * 5^e1; forprime(p=7,, e=valuation(n,p); if(p%4==1, if(e1Charles R Greathouse IV, Dec 10 2016

PARI

See Greathouse link.