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A191856 First factor in happy factorization of n-th rhombic number. 7
1, 7, 2, 1, 3, 1, 23, 4, 1, 31, 16, 5, 2, 1, 47, 6, 1, 1, 7, 1, 71, 25, 79, 8, 1, 3, 4, 13, 48, 9, 103, 2, 1, 5, 119, 10, 1, 127, 64, 1, 27, 34, 1, 11, 151, 4, 3, 80, 1, 167, 12, 1, 7, 22, 1, 1, 191, 96, 13, 199, 2, 8, 1, 43, 4, 73, 223, 14, 1, 3, 2, 5, 239 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) = A007966(A007970(n)) = A007970(n) / A191857(n);

(a(n), A191857(n)) is a 2-happy couple;

notation: D in the Conway link.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..99

J. H. Conway, On Happy Factorizations, J. Integer Sequences, Vol. 1, 1998, #1.

PROG

(Haskell)

a191856 = a007966 . a007970  -- Reinhard Zumkeller, Oct 11 2015

CROSSREFS

Cf. A007966, A007970, A191857.

Sequence in context: A197184 A089129 A100957 * A220862 A198229 A133362

Adjacent sequences:  A191853 A191854 A191855 * A191857 A191858 A191859

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jun 18 2011

EXTENSIONS

Wrong formula removed (thanks to Wolfdieter Lang, who pointed this out) by Reinhard Zumkeller, Oct 11 2015

STATUS

approved

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Last modified July 12 22:46 EDT 2020. Contains 335669 sequences. (Running on oeis4.)