A331435 a(n) is the least positive k such that A028916(n) - k^2 is a fourth power.
1, 2, 1, 6, 5, 4, 10, 11, 10, 14, 15, 1, 14, 5, 9, 20, 21, 24, 19, 4, 6, 26, 26, 12, 14, 29, 16, 31, 29, 22, 24, 31, 34, 1, 26, 5, 28, 35, 40, 19, 41, 39, 44, 38, 29, 45, 42, 4, 6, 35, 51, 16, 46, 20, 51, 54, 55, 56, 56, 30, 52, 54, 34, 36, 56, 58, 40, 9, 11
Offset: 1
Keywords
Examples
The first terms, alongside A028916(n), are: n a(n) A028916(n) -- ---- ---------------- 1 1 2 = 1^2 + 1^4 2 2 5 = 2^2 + 1^4 3 1 17 = 1^2 + 2^4 4 6 37 = 6^2 + 1^4 5 5 41 = 5^2 + 2^4 6 4 97 = 4^2 + 3^4 7 10 101 = 10^2 + 1^4 8 11 137 = 11^2 + 2^4 9 10 181 = 10^2 + 3^4 10 14 197 = 14^2 + 1^4
Links
- Rémy Sigrist, Table of n, a(n) for n = 1..10000
- Rémy Sigrist, PARI program for A331435
- Wikipedia, Friedlander-Iwaniec theorem
Crossrefs
Programs
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PARI
See Links section.