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 A050520 Values of phi in arithmetic progression of at least 6 terms having the same value of phi in A050518. 6
 155520, 311040, 466560, 622080, 777600, 933120, 933120, 1244160, 1399680, 1555200, 1555200, 1866240, 1866240, 1866240, 2332800, 2488320, 2488320, 2799360, 2799360, 3110400, 2799360, 3110400, 3421440, 3732480, 3888000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The values of phi for terms between 13413600 and 10^9 (see comment on A050518) are 3732480, 3888000, 3732480, 4199040, 3732480, 4354560, 4665600, 4665600, 4976640, 4665600, 14999040, 19595520, 29998080, 44130240, 39191040, 44997120, 58786560, 59996160, 88260480, 78382080, 132390720, 134648640, 145313280, 176520960, 220651200, 237948480, 264781440. - Mauro Fiorentini, Apr 17 2015 LINKS Robert Israel, Table of n, a(n) for n = 1..114 Tanya Khovanova, Non Recursions MAPLE N:= 10^7: # to get all terms <= N in A050518 with(numtheory): Res:= NULL: phis:= {seq(phi(i), i=2..N)}: for m in phis do S:= convert(invphi(m), set); if nops(S) < 6 then next fi; for d from 0 to 4 do Sd[d]:= select(t-> (t mod 5 = d), S, d); nd:= nops(Sd[d]); for i0 from 1 to nd-1 do s0:= Sd[d][i0]; if s0 > N then break fi; for i5 from i0+1 to nd do s5:= Sd[d][i5]; incr:= (s5 - s0)/5; if {s0+incr, s0+2*incr, s0+3*incr, s0+4*incr} subset S then Res:= Res, [s0, m]; fi od od; od; od: map2(op, 2, sort([Res], (s, t)->s[1]

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Last modified December 1 23:44 EST 2022. Contains 358485 sequences. (Running on oeis4.)