A097021 Initial terms of chains consisting of five consecutive integers, for neither of which the value of sigma-function is divisible by six.

211248, 1146096, 3948048, 6090048, 14590800, 54100800, 61051248, 315758448, 567777600, 1715222448, 1912711248, 2408874048, 2636106048, 2744664048, 2811450096, 3304032048, 4647444048, 4832821296, 6020336448, 6028239600, 6739372800, 7824754800, 10110704400

Offset

1,1

Comments

In A084301, that is among remainders of sigma(n) modulo 6, chains of 0's can be large. On the contrary, the length of non-0-remainder-chains is believed to be limited or occurrence of longer chains is rare. Consider remainders of sigma(5x) modulo 6.

The first 1000 terms are all divisible by 144. - Donovan Johnson, Aug 07 2013

Links

Donovan Johnson, Table of n, a(n) for n = 1..1000

Example

n = 14590800: sigma values for {n, n+1, n+2, n+3, n+4} = {59658880, 15110144, 22806063, 20958080, 25533914} have remainders modulo 6 as follows {4,2,3,2,2}.

Prog

(PARI) forstep(m=25, 10110704400, 25, if(sigma(m)%6<>0, n=m; c=1; forstep(j=m-1, m-4, -1, if(sigma(j)%6<>0, c++; n=j, j=m-4)); for(j=m+1, m+4, if(sigma(j)%6<>0, c++, j=m+4)); if(c>=5, print1(n ", ")))) /* Donovan Johnson, Aug 06 2013 */

Crossrefs

Cf. A084301.

Sequence in context: A178421 A069175 A340158 * A236086 A123103 A259756

Adjacent sequences: A097018 A097019 A097020 * A097022 A097023 A097024

Keyword

nonn

Author

Labos Elemer, Aug 23 2004

Extensions

a(6)-a(20) from Donovan Johnson, Sep 03 2008

Status

approved