OFFSET
1,1
COMMENTS
Partial sums of sub-perfect powers: perfect powers (squares, cubes, etc.) minus 1. The subsequence of primes in the partial sum begins: 3, 83, 149, 197, 439, 683, 953, 1531, 1997, 9311, 10151, 13009. The subsequence of subperfect powers in the partial sum (numbers n such that n-1 is a perfect power) begins: 10 (because 10-1=9=3^2), 197 because 197-1=196=2^2 * 7^2.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
FORMULA
EXAMPLE
a(40) = 3 + 7 + 8 + 15 + 24 + 26 + 31 + 35 + 48 + 63 + 80 + 99 + 120 + 124 + 127 + 143 + 168 + 195 + 215 + 224 + 242 + 255 + 288 + 323 + 342 + 360 + 399 + 440 + 483 + 511 + 528 + 575 + 624 + 675 + 728 + 783 + 840 + 899 + 960 + 999 = 13009 is prime.
MAPLE
N:= 10^4:
P:= sort(convert({seq(seq(i^p-1, p=2..floor(log[i](N))), i=2..isqrt(N))}, list)):
ListTools:-PartialSums(P); # Robert Israel, Jul 06 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, May 16 2010
STATUS
approved