A069534 Smallest multiple of 5 with digit sum n.

10, 20, 30, 40, 5, 15, 25, 35, 45, 55, 65, 75, 85, 95, 195, 295, 395, 495, 595, 695, 795, 895, 995, 1995, 2995, 3995, 4995, 5995, 6995, 7995, 8995, 9995, 19995, 29995, 39995, 49995, 59995, 69995, 79995, 89995, 99995, 199995, 299995, 399995, 499995, 599995

Offset: 1

Author

Amarnath Murthy, Apr 01 2002

Keywords

• base
• nonn
• easy

Comments

a(6) onwards the pattern is evident.

Links

• Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,0,0,10,-10).

Crossrefs

Cf. A069521 to A069530, A069532, A069533.

Cf. A077492.

Programs

Mathematica

t={}; Do[i=5; While[Total[IntegerDigits[i]]!=n,i=i+5]; AppendTo[t,i],{n,46}]; t (* Jayanta Basu, May 19 2013 *)
With[{f=5*Range[200000]},Flatten[Table[Select[f,Total[IntegerDigits[#]] == n&,1],{n,50}]]] (* Harvey P. Dale, Dec 31 2013 *)

PARI

A069534(n)=(((n+4)%9+1)*10^((n+4)\9)-5)*10^(n<5) \\ M. F. Hasler, Sep 16 2016

Formula

a(n) = ((n+4)%9+1)*10^floor((n+4)/9)-5 for all n > 4, where % is the binary mod/remainder operator. - M. F. Hasler, Sep 16 2016

From Chai Wah Wu, Sep 15 2020: (Start)

a(n) = a(n-1) + 10*a(n-9) - 10*a(n-10) for n > 14.

G.f.: 5*x*(72*x^13 - 18*x^12 - 18*x^11 - 18*x^10 - 18*x^9 + 2*x^8 + 2*x^7 + 2*x^6 + 2*x^5 - 7*x^4 + 2*x^3 + 2*x^2 + 2*x + 2)/((x - 1)*(10*x^9 - 1)). (End)

a(n) = 5 * A077492(n). - Alois P. Heinz, Sep 15 2020

Extensions

More terms from Ray Chandler, Jul 28 2003