The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A292033

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A292033

Unitary phibonacci numbers: solutions k of the equation uphi(k) = uphi(k-1) + uphi(k-2), where uphi(k) is the unitary totient function (A047994).
(history; published version)

#14 by Michel Marcus at Sun Mar 01 04:40:40 EST 2020

STATUS

reviewed

approved

#13 by Joerg Arndt at Sun Mar 01 04:37:00 EST 2020

STATUS

proposed

reviewed

#12 by Amiram Eldar at Sun Mar 01 04:25:51 EST 2020

STATUS

editing

proposed

#11 by Amiram Eldar at Sun Mar 01 03:36:38 EST 2020

NAME

Unitary phibonacci numbers: solutions n k of the equation uphi(nk) = uphi(nk-1) + uphi(nk-2), where uphi(nk) is the unitary totient function (A047994).

DATA

3, 4, 7, 23, 9179, 244967, 14307856, 24571871, 128199059, 140830367, 401767631, 420567856, 468190439, 525970979, 780768167, 886434647, 1597167647, 4046753951, 4473784823, 5364666167, 5515718207, 11175736336, 14408460167, 18026319712, 20106993887, 20357733131

PROG

(PARI) uphi(n) = my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[1, i, 2]-1);

KEYWORD

nonn,more

nonn

EXTENSIONS

a(18)-a(26) from Amiram Eldar, Mar 01 2020

STATUS

approved

editing

#10 by Bruno Berselli at Thu Sep 20 08:16:35 EDT 2018

STATUS

proposed

approved

#9 by Michel Marcus at Thu Sep 20 08:03:01 EDT 2018

STATUS

editing

proposed

#8 by Michel Marcus at Thu Sep 20 08:02:58 EDT 2018

PROG

(PARI) uphi(n) = prodmy(i=1, #nf=factor(n)~, n[); prod(i=1, #f~, f[i, 1]^nf[1, 2, i]-1);

STATUS

approved

editing

#7 by N. J. A. Sloane at Sat Sep 09 21:36:06 EDT 2017

STATUS

proposed

approved

#6 by Altug Alkan at Fri Sep 08 14:32:15 EDT 2017

STATUS

editing

proposed

#5 by Altug Alkan at Fri Sep 08 14:31:08 EDT 2017

PROG

(PARI) uphi(n) = prod(i=1, #n=factor(n)~, n[1, i]^n[2, i]-1);

isok(n) = uphi(n)==uphi(n-1)+uphi(n-2); \\ Altug Alkan, Sep 08 2017

STATUS

proposed

editing