A067234 Numbers n such that phi(4n+1) = sigma(n).

56, 476, 2840, 4676, 8120, 9416, 16256, 23940, 25056, 28520, 30566, 32760, 36146, 37716, 39816, 55676, 56306, 65280, 66056, 129260, 135840, 143096, 149960, 155876, 176736, 185240, 198240, 198396, 202676, 232596, 252756, 257312, 296786

Offset

1,1

Comments

Are there any odd terms in the sequence?

Links

Donovan Johnson, Table of n, a(n) for n = 1..1000

Mathematica

Select[Range[300000], EulerPhi[4#+1]==DivisorSigma[1, #]&] (* Harvey P. Dale, Apr 14 2022 *)

Prog

(PARI) for(n=1, 10^9, if(eulerphi(4*n+1)==sigma(n), print(n))) /* Donovan Johnson, Aug 18 2012 */

Crossrefs

Sequence in context: A187159 A220048 A257707 * A244358 A219832 A219576

Adjacent sequences: A067231 A067232 A067233 * A067235 A067236 A067237

Keyword

nonn

Author

Benoit Cloitre, Feb 20 2002

Status

approved