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A171743 a(n) = A000010(A001043(n)). 2
4, 4, 4, 6, 8, 8, 12, 12, 24, 16, 32, 24, 24, 24, 40, 48, 32, 64, 44, 48, 72, 54, 84, 60, 60, 64, 48, 72, 72, 64, 84, 132, 88, 96, 80, 120, 128, 80, 128, 160, 96, 120, 128, 96, 120, 160, 180, 120, 144, 120, 232, 128, 160, 252, 192, 216, 144, 272, 180, 184, 192, 160 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(n) = phi(prime(n) + prime(n+1)).
MAPLE
A000010 := proc(n) numtheory[phi](n); end proc: A001043 := proc(n) ithprime(n)+ithprime(n+1) ; end proc: A171743 := proc(n) A000010(A001043(n)) ; end proc: for n from 1 to 100 do printf("%d, ", A171743(n)) ; od: # R. J. Mathar, Jan 21 2010
MATHEMATICA
EulerPhi[Total[#]]&/@Partition[Prime[Range[70]], 2, 1] (* Harvey P. Dale, Mar 05 2013 *)
PROG
(PARI) p=2; forprime(q=3, 1e3, print1((p-1)*(q-1)", "); p=q) \\ Charles R Greathouse IV, Feb 21 2013
CROSSREFS
Sequence in context: A256417 A229630 A141466 * A295641 A171815 A023958
KEYWORD
easy,nonn
AUTHOR
Giovanni Teofilatto, Dec 17 2009
EXTENSIONS
Corrected (a(36)=204 removed) by R. J. Mathar, Jan 21 2010
STATUS
approved

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Last modified March 29 03:51 EDT 2024. Contains 371264 sequences. (Running on oeis4.)