OFFSET
1,1
COMMENTS
Original name: A subset of A056912, definition unclear.
The definition is given on page 70 of Gupta (1943), but is hard to understand.
A variant of A056912, which has terms that also have prime factors > 31. - Arkadiusz Wesolowski, Jan 21 2016
The b-file contains the full sequence.- Robert Israel, Jan 21 2016
REFERENCES
H. Gupta, A formula for L(n), J. Indian Math. Soc., 7 (1943), 68-71.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Robert Israel, Table of n, a(n) for n = 1..512
H. Gupta, A formula for L(n), J. Indian Math. Soc., 7 (1943), 68-71. [Annotated scanned copy]
MAPLE
S:= select(t -> (nops(t)::odd), combinat:-powerset(select(isprime, [seq(i, i=3..31, 2)]))):
sort(map(convert, S, `*`)); # Robert Israel, Jan 21 2016
MATHEMATICA
osfnQ[n_]:=SquareFreeQ[n]&&OddQ[PrimeOmega[n]]&&Max[FactorInteger[n][[All, 1]]]<32; Select[Range[1, 1301, 2], osfnQ] (* Harvey P. Dale, Jul 19 2019 *)
PROG
(Magma) a:= func< n | Factorization(n)>; [n: n in [3..1265 by 2] | IsSquarefree(n) and (-1)^&+[p[2]: p in a(n)] eq -1 and f[#f][1] le 31 where f is a(n)]; // Arkadiusz Wesolowski, Jan 21 2016
(PARI) isok(n) = (n % 2) && issquarefree(n) && (omega(n) % 2) && (vecmax(factor(n)[, 1]) <= 31); \\ Michel Marcus, Jan 21 2016
CROSSREFS
KEYWORD
nonn,fini,full
AUTHOR
N. J. A. Sloane, Oct 07 2015
EXTENSIONS
Name changed and sequence extended by Arkadiusz Wesolowski, Jan 21 2016
STATUS
approved