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Index to OEIS: Section U

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Index to OEIS: Section U


[ Aa | Ab | Al | Am | Ap | Ar | Ba | Be | Bi | Bl | Bo | Br | Ca | Ce | Ch | Cl | Coa | Coi | Com | Con | Cor | Cu | Cy | Da | De | Di | Do | Ea | Ed | El | Eu | Fa | Fe | Fi | Fo | Fu | Ga | Ge | Go | Gra | Gre | Ha | He | Ho | Ia | In | J | K | La | Lc | Li | Lo | Lu | M | Mag | Map | Mat | Me | Mo | Mu | N | Na | Ne | Ni | No | Nu | O | Pac | Par | Pas | Pea | Per | Ph | Poi | Pol | Pos | Pow | Pra | Pri | Pro | Ps | Qua | Que | Ra | Rea | Rel | Res | Ro | Ru | Sa | Se | Si | Sk | So | Sp | Sq | St | Su | Sw | Ta | Te | Th | To | Tra | Tri | Tu | U | V | Wa | We | Wi | X | Y | Z | 1 | 2 | 3 | 4 ]


U-coordinates for arrays: see T-coordinates for arrays
ugly numbers: A051037
Ulam numbers: sequences related to :

Ulam numbers: A002858* A078425

Ulam-type sequences: A002858*, A001857, A003664, A007300, A003668, A002859, A003669, A003666, A006844, A003662, A003670, A003667, A003663, A117140
unary representations: A000042
unary-binary tree, definition: A029766
undecagon is spelled 11-gon in the OEIS
undulating numbers: A033619*
undulating squares: A016073
unexplained differences between partition generating functions: A007326, A007327, A007328, A007329, A007330
unhappy numbers: A031177
unidecagon is spelled 11-gon in the OEIS
Unions and sums:: A003430
unique factorization domains: A003172*
unit fractions: see Egyptian fractions
unit interval graphs: see interval graphs
unitary amicable numbers: A002952*, A002953*
unitary divisors of n, number of: A034444*
unitary divisors of n, sum of: A034448*
unitary divisors: see also (1) A002827 A033854 A033857 A033858 A033859 A034460 A034676 A034677 A034678 A034679 A034680 A034681
unitary divisors: see also (2) A034682 A034684 A037176 A046971
unitary perfect numbers: A002827*
unitary phi function uphi: see unitary totient function
unitary totient function uphi: A047994*, A049865, A003271
universal quadratic forms: A030050, A030051, A116582, A154363
unpredictable sequence: A007061
unsolved problems in number theory (selected):  :

unsolved problems in number theory (selected): A000069, A001220, A001969, A002496, A036262, A070087, A070089, A070176, A07019, A144914
unsolved problems in number theory: see also Goldbach conjecture
unsolved problems in number theory: see also Riemann hypothesis
unsolved problems in number theory: see also: sequences that need extending

untouchable numbers: A005114*
up-down permutations: A000111*
urinals: see pay-phones
urns: A003125, A003126, A003127, A063169, A063170
usigma(n): A034448*


[ Aa | Ab | Al | Am | Ap | Ar | Ba | Be | Bi | Bl | Bo | Br | Ca | Ce | Ch | Cl | Coa | Coi | Com | Con | Cor | Cu | Cy | Da | De | Di | Do | Ea | Ed | El | Eu | Fa | Fe | Fi | Fo | Fu | Ga | Ge | Go | Gra | Gre | Ha | He | Ho | Ia | In | J | K | La | Lc | Li | Lo | Lu | M | Mag | Map | Mat | Me | Mo | Mu | N | Na | Ne | Ni | No | Nu | O | Pac | Par | Pas | Pea | Per | Ph | Poi | Pol | Pos | Pow | Pra | Pri | Pro | Ps | Qua | Que | Ra | Rea | Rel | Res | Ro | Ru | Sa | Se | Si | Sk | So | Sp | Sq | St | Su | Sw | Ta | Te | Th | To | Tra | Tri | Tu | U | V | Wa | We | Wi | X | Y | Z | 1 | 2 | 3 | 4 ]


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