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A171815
Values of A171743 that are 1 less than a prime, listed in the order in which they appear.
0
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
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
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