A309238 Non-prime-square numbers equal to the sum of squares of consecutive primes from the least prime factor to the largest prime factor.
315797, 9634877
Offset: 1
Examples
9634877 = 7 * 41 * 59 * 569 = 7^2 + 11^2 + 13^2 + ... + 569^2.
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.
Crossrefs
Cf. A055233.
Programs
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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
Comments