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1,1
Searched up to n = 5000.
a(4) has 38019 digits (1973212031 ... 7493445627) and corresponds to n=9553. - Robert Price, Sep 23 2016; [number of digits in a(4) corrected by Jon E. Schoenfield, Nov 06 2016]
No other primes corresponding to n < 80000. - Robert Price, Mar 17 2017
Table of n, a(n) for n=1..3.
Sebastiao Antonio da Silva, Prime Curios: 9^8 + 8^7 + 7^6 + 6^5 + 5^4 + 4^3 + 3^2 + 2^1 + 1^0 is prime
3 is in the sequence because 3 is prime and 3 = 2^1 + 1^0.
701 is in the sequence because 701 is prime and 701 = 5^4 + 4^3 + 3^2 + 2^1 + 1^0.
45269999 is in the sequence because 45269999 is prime and 45269999 = 9^8 + 8^7 + 7^6 + 6^5 + 5^4 + 4^3 + 3^2 + 2^1 + 1^0.
(Sage)
sum = 0
seq = []
max_n = 2500
for n in range(1, max_n+1):
sum = sum + n^(n-1)
if is_prime(sum):
seq.append(n)
print seq
Primes in A060946.
Sequence in context: A266639 A203496 A308323 * A231604 A306961 A059120
Adjacent sequences: A276452 A276453 A276454 * A276456 A276457 A276458
nonn,bref
Robert C. Lyons, Sep 06 2016
approved