A375242 - OEIS

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A375242

Numbers with digital root in {2, 4, 5, 7, 8}.

2, 4, 5, 7, 8, 11, 13, 14, 16, 17, 20, 22, 23, 25, 26, 29, 31, 32, 34, 35, 38, 40, 41, 43, 44, 47, 49, 50, 52, 53, 56, 58, 59, 61, 62, 65, 67, 68, 70, 71, 74, 76, 77, 79, 80, 83, 85, 86, 88, 89, 92, 94, 95, 97, 98, 101, 103, 104, 106, 107, 110, 112, 113, 115, 116

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Also nontriangular numbers with digital root in {2, 4, 5, 7, 8}.

REFERENCES

Albert H. Beiler, Recreations in the theory of numbers, New York, Dover, (2nd ed.) 1966. See p. 190.

LINKS

Stefano Spezia, Table of n, a(n) for n = 1..10000

Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,1,-1).

FORMULA

G.f.: x*(2 + 2x + x^2 + 2*x^3 + x^4 + x^5)/((1 - x)^2*(1 + x + x^2 + x^3 + x^4)).

a(n) ~ 9*n/5.

MATHEMATICA

A010888[n_]:=If[n>0, n - 9*Floor[(n-1)/9], 0]; Select[Range[0, 130], MemberQ[{2, 4, 5, 7, 8}, A010888[#]] &]

PROG

(PARI) list(lim)=my(v=List()); forstep(n=2, lim\1, [2, 1, 2, 1, 3], listput(v, n)); Vec(v) \\ Charles R Greathouse IV, Aug 07 2024

(PARI) is(n)=!setsearch([0, 1, 3, 6], n%9) \\ Charles R Greathouse IV, Aug 07 2024

CROSSREFS

Complement of A055264. Complement of A375241 in A014132.

Cf. A010888.

Sequence in context: A262978 A112886 A282429 * A111040 A191324 A147807

Adjacent sequences: A375239 A375240 A375241 * A375243 A375244 A375245

KEYWORD

nonn,base,easy

AUTHOR

Stefano Spezia, Aug 07 2024

STATUS

approved