OFFSET
1,1
COMMENTS
So-called 2-straddled numbers; 1-straddled numbers are in A055233.
a(3) > 7*10^14, if it exists. - Giovanni Resta, Jul 18 2019
LINKS
M. Kures, Straddled numbers: numbers equal to the sum of powers of consecutive primes from the least prime factor to the largest prime factor, Notes on Number Theory and Discrete Mathematics, 2019, vol. 25, no. 2, pp. 8-15. ISSN: 1310-5132.
EXAMPLE
9634877 = 7 * 41 * 59 * 569 = 7^2 + 11^2 + 13^2 + ... + 569^2.
PROG
(PARI) isok(n) = if (isprimepower(n) != 2, if (n>1, my(f=factor(n)[, 1], s=0); forprime(p=vecmin(f), vecmax(f), s+= p^2); s == n)); \\ Michel Marcus, Jul 18 2019
CROSSREFS
KEYWORD
nonn,more,bref
AUTHOR
Miroslav Kures, Jul 17 2019
STATUS
approved