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A005073 Sum of 4th powers of primes = 1 mod 3 dividing n. 5
0, 0, 0, 0, 0, 0, 2401, 0, 0, 0, 0, 0, 28561, 2401, 0, 0, 0, 0, 130321, 0, 2401, 0, 0, 0, 0, 28561, 0, 2401, 0, 0, 923521, 0, 0, 0, 2401, 0, 1874161, 130321, 28561, 0, 0, 2401, 3418801, 0, 0, 0, 0, 0, 2401, 0, 0, 28561, 0, 0, 0, 2401, 130321, 0, 0, 0, 13845841, 923521, 2401, 0, 28561, 0, 20151121, 0, 0, 2401, 0, 0, 28398241, 1874161 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,7
LINKS
FORMULA
Additive with a(p^e) = p^4 if p = 1 (mod 3), 0 otherwise.
MATHEMATICA
f[p_, e_] := If[Mod[p, 3] == 1, p^4, 0]; a[n_] := Plus @@ f @@@ FactorInteger[n]; a[1] = 0; Array[a, 100] (* Amiram Eldar, Jun 21 2022 *)
PROG
(Scheme) (define (A005073 n) (if (= 1 n) 0 (+ (A000583 (if (= 1 (modulo (A020639 n) 3)) (A020639 n) 0)) (A005073 (A028234 n))))) ;; Antti Karttunen, Jul 09 2017
(PARI) a(n) = my(f=factor(n)); sum(k=1, #f~, if (((p=f[k, 1])%3) == 1, p^4)); \\ Michel Marcus, Jul 10 2017
CROSSREFS
Sequence in context: A235414 A235259 A321638 * A176767 A018865 A186488
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Antti Karttunen, Jul 09 2017
STATUS
approved

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Last modified April 12 20:17 EDT 2024. Contains 371636 sequences. (Running on oeis4.)