

A122484


Numbers n not ending in zero such that the sum of digits of n is >= the sum of digits of n^4 (in base 10).


3




OFFSET

1,2


COMMENTS

I've also found 498998999999, 7494994999999, 34999974999999 and some larger numbers, but not all values in between have been checked.
One is likely to find an example of the form 5*10^nm*10^floor[n/2]1 or 7.5*10^nm*10^floor[n/2]1 for n>12 within the first 10^(floor[n/2]1) m's.
Is this sequence finite?  Charles R Greathouse IV, Jan 12 2012
This sequence is infinite: for N=7.5*10^n40*10^[n/2]1 one has A007953(N)=9n2 and A007953(N^4) <= 9n2 for all n>16, with equality for all even n>16.  M. F. Hasler, Jan 14 2012


LINKS

Table of n, a(n) for n=1..9.


FORMULA

A122484 = { n in A067251  A007953(n) >= A007953(n^4) }.  M. F. Hasler, Jan 14 2012


EXAMPLE

67 is in the list because 67 has a digital sum of 13 and 67^4 = 20151121 which also has a digital sum of 13.
594959999 has a digital sum of 68 and 594959999^4 has a digital sum of 67, i.e. less than 68.


PROG

(PARI) is_A122484(n)= n%10 && A007953(n) >= A007953(n^4) \\ M. F. Hasler, Jan 14 2012


CROSSREFS

Cf. A064210.
Sequence in context: A046137 A193643 A228026 * A155242 A155333 A155296
Adjacent sequences: A122481 A122482 A122483 * A122485 A122486 A122487


KEYWORD

base,nonn


AUTHOR

Martin Raab, Sep 15 2006


EXTENSIONS

a(8) and a(9) from Martin Raab, Oct 17 2008


STATUS

approved



