A171815 Values of A171743 that are 1 less than a prime, listed in the order in which they appear.

4, 4, 4, 6, 12, 12, 16, 40, 72, 60, 60, 72, 72, 88, 96, 96, 96, 180, 232, 192, 180, 192, 192, 352, 192, 280, 432, 240, 240, 420, 240, 408, 336, 432, 352, 592, 600, 408, 336, 640, 616, 456, 448, 576, 432, 672, 432, 400, 432, 448, 600, 928, 576, 672, 928, 672, 1008

Offset

1,1

Links

Table of n, a(n) for n=1..57.

Mathematica

Do[a=EulerPhi[Prime[n] + Prime[n+1]]; If[PrimeQ[a+1], Print[a]], {n, 2^10}] (* Metin Sariyar, Nov 24 2019 *)
Select[EulerPhi[Total[#]]&/@Partition[Prime[Range[200]], 2, 1], PrimeQ[#+1]&] (* Harvey P. Dale, Dec 25 2022 *)

Crossrefs

Cf. A000010, A001043, A171743.

Sequence in context: A141466 A171743 A295641 * A023958 A137751 A244481

Adjacent sequences: A171812 A171813 A171814 * A171816 A171817 A171818

Keyword

easy,nonn

Author

Giovanni Teofilatto, Dec 19 2009

Extensions

a(14) corrected and terms beyond a(14) appended by R. J. Mathar, Jan 30 2010

Named edited by Michel Marcus, Nov 24 2019

Status

approved