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A076705
Prime powers of prime numbers such that the sum of its digits is also prime power of prime number.
1
4, 8, 9, 27, 121, 125, 243, 1331, 4489, 10201, 12769, 24649, 37249, 66049, 80089, 96721, 113569, 139129, 167281, 175561, 177147, 214369, 259081, 358801, 371293, 413449, 426409, 436921, 552049, 579121, 591361, 635209, 823543, 1026169
OFFSET
1,1
COMMENTS
Up to 10^7, there are 513 prime powers of prime numbers. Of these, 79 are such that the sum of their digits is also prime power of prime number. Up to 10^14 there are 43915.
LINKS
MAPLE
N:= 2000000: # for terms <= N
R:= NULL:
p:= 1:
do
p:= nextprime(p);
if p^2 > N then break fi;
q:= 1;
do
q:= nextprime(q);
x:= p^q;
if x > N then break fi;
R:= R, x;
od;
od:
S:= {R}:
sort(convert(select(s -> member(convert(convert(s, base, 10), `+`), S), S), list)); # Robert Israel, Apr 06 2020
MATHEMATICA
pp = Sort[ Flatten[ Table[ Prime[n]^Prime[i], {n, 1, PrimePi[ Sqrt[10^14]]}, {i, 1, PrimePi[ Floor[ Log[ Prime[n], 10^14]]]}]]]; a = {}; Do[ If[ Position[pp, Plus @@ IntegerDigits[ pp[[n]] ]] != {}, a = Append[a, pp[[n]] ]], {n, 1, 669541}]
CROSSREFS
Sequence in context: A075783 A098121 A115656 * A306916 A355063 A162752
KEYWORD
nonn,base
AUTHOR
Zak Seidov, Oct 26 2002
EXTENSIONS
Edited and corrected by Robert G. Wilson v, Oct 31 2002
STATUS
approved