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A306277 Numbers congruent to 1 or 8 mod 10. 4
1, 8, 11, 18, 21, 28, 31, 38, 41, 48, 51, 58, 61, 68, 71, 78, 81, 88, 91, 98, 101, 108, 111, 118, 121, 128, 131, 138, 141, 148, 151, 158, 161, 168, 171, 178, 181, 188, 191, 198, 201, 208, 211, 218, 221, 228, 231, 238, 241, 248, 251, 258, 261, 268, 271, 278, 281, 288, 291, 298, 301, 308, 311, 318, 321 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A007310(a(n)+1) is always a multiple of 5.

a(1) = 1, a(n+1) = a(n)+7 when n is odd, a(n+1) = a(n)+3 when n is even.

a(n) mod 6 follows the following pattern: 1,2,5,0,3,4,1,2,5,0,3,4, and so on.

A020639(A007310(a(n)+1)) = 5.

LINKS

Davis Smith, Table of n, a(n) for n = 1..1000

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

FORMULA

a(n) = 5*n - 2*A000034(n+1).

a(n) = a(n-1) + a(n-2) - a(n-3) for n>3.

a(n) = A273669(n) - 1. - Antti Karttunen, Feb 07 2019

G.f.: x*(1 + 7*x + 2*x^2) / ((1 - x)^2*(1 + x)). - Colin Barker, Feb 09 2019

MAPLE

seq(seq(10*i+j, j=[1, 8]), i=0..350);

MATHEMATICA

Select[Range[350], MemberQ[{1, 8}, Mod[#, 10]] &]

PROG

(PARI) for(n=1, 350, if((n%10==1) || (n%10==8), print1(n, ", ")))

(PARI) Vec(x*(1 + 7*x + 2*x^2) / ((1 - x)^2*(1 + x)) + O(x^40)) \\ Colin Barker, Feb 09 2019

CROSSREFS

Cf. A020639, A007310, A000034.

Cf. A017281, A017365 (bisections).

One less than A273669.

Sequence in context: A118549 A299979 A291663 * A067469 A237767 A284324

Adjacent sequences:  A306274 A306275 A306276 * A306278 A306279 A306280

KEYWORD

nonn,easy,base

AUTHOR

Davis Smith, Feb 02 2019

STATUS

approved

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Last modified January 27 08:31 EST 2020. Contains 331293 sequences. (Running on oeis4.)