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A278162 Least number with the prime signature of n^2 + 1. 5
1, 2, 2, 6, 2, 6, 2, 12, 6, 6, 2, 6, 6, 30, 2, 6, 2, 30, 12, 6, 2, 30, 6, 30, 2, 6, 2, 30, 6, 6, 6, 30, 12, 30, 6, 6, 2, 30, 12, 6, 2, 12, 6, 60, 6, 6, 6, 210, 6, 6, 6, 6, 6, 30, 2, 30, 2, 120, 6, 6, 6, 6, 6, 30, 6, 6, 2, 30, 24, 6, 12, 6, 30, 210, 2, 30, 6, 30, 6, 6, 6, 30, 12, 210, 2, 6, 6, 30, 6, 30, 2, 30, 6, 60, 2, 6, 6, 30, 30, 60, 6, 6, 6, 30, 6, 30, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
FORMULA
a(n) = A046523(A002522(n)) = A046523((n^2)+1).
a(n) = A278260(2*n).
MATHEMATICA
Table[Times @@ MapIndexed[(Prime@ First@ #2)^#1 &, #] &@ If[Length@ # == 1 && #[[1, 1]] == 1, {0}, Reverse@ Sort@ #[[All, -1]]] &@ FactorInteger[ n^2 + 1], {n, 0, 120}] (* Michael De Vlieger, Nov 21 2016 *)
PROG
(PARI)
A046523(n) = my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]) \\ From Charles R Greathouse IV, Aug 17 2011
A278162(n) = A046523((n^2)+1);
for(n=0, 10000, write("b278162.txt", n, " ", A278162(n)));
(Scheme) (define (A278162 n) (A046523 (+ 1 (* n n))))
CROSSREFS
Bisection of A278260.
Cf. A005574 (positions of 2's), A085722 (of 6's).
Cf. also A278160, A278244, A278254.
Sequence in context: A080404 A247451 A167268 * A187223 A349921 A175194
KEYWORD
nonn
AUTHOR
Antti Karttunen, Nov 19 2016
STATUS
approved

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Last modified March 28 07:48 EDT 2024. Contains 371235 sequences. (Running on oeis4.)