A112721 - OEIS

A112721

Numbers n such that phi(n)=d_1^1+d_2^2+...+d_k^k where d_1 d_2 ... d_k is the decimal expansion of n.

1, 44, 84, 5676, 32186, 35097, 128476, 527048, 700298, 12141094, 43874279, 58730238, 303387848, 2277279428

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

a(15) > 6*10^10. - Donovan Johnson, Nov 09 2010

All terms of this sequence are less than 2 * 10^42. - Charles R Greathouse IV, May 11 2012

a(15) > 10^12. - Giovanni Resta, Apr 12 2017

LINKS

EXAMPLE

phi(12141094)=1^1+2^2+1^3+4^4+1^5+0^6+9^7+4^8 so 12141094 is in

the sequence.

MATHEMATICA

Do[d=IntegerDigits[n]; k=Length[d]; If[EulerPhi[n]==Sum[d[[j]]^j, {j, k}], Print[n]], {n, 30000000}]

CROSSREFS

KEYWORD

base,fini,more,nonn

AUTHOR

EXTENSIONS

a(11)-a(12) from Farideh Firoozbakht, Jan 04 2009

a(13)-a(14) from Donovan Johnson, Nov 09 2010

STATUS

approved